JPS582555B2 - Automatic back up system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a backup system for an automatic control device.

Conventional backup systems have two automatic control devices with identical circuit configurations, one of which is used regularly and the other one as a backup, or if the automatic control device fails, it can be used as a manual control device. It was configured to switch.

FIG. 2 shows a conventional non-contact starting device for a pumped storage power plant with direct coupling induction motor starting.

This starting device performs acceleration-uniform speed control of the induction motor 3 directly connected to the generator motor.

As is well known, an induction motor has a slip S-torque τ characteristic as shown in FIG.

The number of poles of the induction motor is 2 to 4 fewer than that of a normal generator motor to make synchronization easier. In the figure, the slip of the induction motor at the synchronous speed of the generator motor is S0, and the torque of the induction motor at constant torque acceleration. is shown as τ0.

Curve C1 is the loss torque characteristic of the generator motor, curve C2 is the slip-torque characteristic when the secondary resistance R2 of the induction motor is zero, point A is the synchronization point, and curves C3 to C7 are the loss torque characteristics of the induction motor when the secondary resistance R2 is zero. The slip-torque characteristics are shown when the changes are made.

Curve C2 is the case when the secondary resistance R2 is maximum, and curves C4 to C
7 is the case where the secondary resistance R2 is gradually decreased from now on, and in particular, the curve C6 is the case where the secondary resistance R2 is synchronous.

If the primary current of the induction motor is I1, the torque τ is approximately given by the following formula.

τ=KI1 (K: constant) Therefore, it is well known that if the primary current ■1 is kept constant, the torque τ can be kept constant, and the starting device is based on this principle, and the slip S1 will be described later. It shows the speed at which the operating point of the speed relay 95 switches from constant torque acceleration to uniform speed control that performs parallel operation to the generator motor system.

In FIG. 2, a generator motor 1 has a field winding 2, a parallel circuit breaker 7, an instrument transformer 8, and an automatic parallel device 9 are connected via a phase switching disconnector 36, and its rotating shaft A tachometer generator 5 is connected to the tachometer generator 5, and its output is connected to a speed relay 95 for switching from constant torque acceleration to constant speed control.

The induction motor 3 has a secondary resistance 4 for speed adjustment, and a circuit breaker 1
The primary current flowing through 0 is taken out by a current transformer 11, converted to voltage by a current-voltage converter 12, and input to an operational amplifier 160 via a contact 14 of a speed relay that turns on below the slip S1. is applied to

A primary current setting device 13 for performing constant torque acceleration is connected to this input via a contact that interlocks with the contact 14, and furthermore, an increasing side voltage setting device 19 and a decreasing side voltage setting device 20 at constant speed are connected. A contact 17 turns on when the speed increases, and a contact 18 and a contact 15 turn on when the speed decreases, respectively, of the uniform speed signal.
connected via.

The output of the operational amplifier 16 is supplied to a gate pulse generator 22 via a gate circuit, and the gate pulse is applied to a speed increasing thyristor 23 or a speed decreasing thyristor 24 to trigger it, and has a field winding 26. The armature 25 of the shunt motor is driven once by switching the current from the power source 28 flowing into the armature 25.

The rotation of the shunt motor is controlled by the induction motor 3 via the drive gear 27.
The signal is transmitted to the secondary resistor 4, which is adjusted.

Now, in the case of pumped water start-up, switch the phase switching disconnector 36 to the motor side, set the speed adjustment resistor 4 to the maximum position, turn on the resistor R2 of curve C3 in Figure 3, and set it at the position where constant torque τ0 is generated, and shut off. Insert the container 10.

The primary current 1 of the induction motor 3 is detected by the current transformer 11, the output voltage of the current-voltage converter 12 and the set voltage of the primary current setter 13 are compared, and the operational amplifier 16 and the gate circuit 21 The gate pulse generator 22 triggers the thyristor 23 or 24 to drive the shunt motor, and the secondary resistor 4 is controlled via the drive gear 27 so that τ0=KI1.

As a result, the induction motor and generator motor are accelerated with τ0 constant.

In this case, the field winding 2 is energized during the control to cause the generator motor 1 to generate voltage.

When the speed increases and reaches the slip S1, the speed relay operates and its contacts 14 and 15 switch from constant torque acceleration to constant speed control.

The automatic paralleling device 9 compares the phase between the generator motor 1 and the grid, and if the generator motor speed is delayed, the contact 17 is turned on and the voltage of the voltage setting device 19 is applied to the operational amplifier 16, thereby increasing the speed of the shunt motor. Conversely, if the speed of the generator motor is fast, the contact 18 is turned on to apply the voltage from the voltage setter 20 to the operational amplifier 16, and the shunt motor is driven to the speed down side to match the phase of the system.

When the voltage, frequency, and phase match as described above, the parallel circuit breaker 7 is turned on to complete the parallel operation.

FIG. 3 shows a contact type starting device which has a completely different circuit configuration from the above-mentioned starting device but has substantially the same effects, and the same reference numerals as in FIG. 2 indicate the same or equivalent parts.

In Figure 3, the current detected by the current transformer 11 is supplied to a current relay 29 that turns on below a certain current and a current relay 30 that turns on above a certain current, resulting in a current between the operating levels of both relays. Like, control relay 31,3
2 to perform constant torque acceleration and the speed relay operates, control relays 31 and 3 are activated by uniform speed signal 1γ or 18.
2 and perform parallel operation according to the signal from the automatic parallel device 9.

The conventional starting device described in detail above has the disadvantage that pumped water starting becomes impossible if any one circuit fails.

Therefore, when implementing the method shown in Figure 2, in order to avoid such drawbacks, circuits that are prone to failure may be duplicated and switched using exactly the same circuit configuration, or manual control circuits may be added to the circuits shown in Figures 2 and 3. Measures were taken to enable manual control.

However, when the same circuit is duplicated in this way, it is difficult to avoid recurrence of failures in the same parts, and there is also the drawback that sufficient manual control cannot be performed.

Furthermore, if there is a strong developmental element and there is not much experience, it may be difficult to judge which circuit is easier to adjust and is compatible with the system. I have to make adjustments.

For example, the type shown in Fig. 2 has a long life and is easy to adjust, but is susceptible to surges, and the type shown in Fig. 3 has a simple structure but has a relatively short life, so it is difficult to easily judge whether it is superior or inferior.

Therefore, it is often impossible to test which one is suitable for the system or to judge that the track record is boring.

In order to eliminate the above-mentioned conventional drawbacks, the present invention provides a first automatic control device and a second automatic control device that has a completely different circuit configuration from this automatic control device and performs almost the same operation. By switching between these two automatic control devices and configuring one of them to be engaged with the controlled object using a switch, it is possible to use the one that is easier to use through field tests as the regular circuit, and use the other as a backup circuit. This is the key to preventing recurrence of failures caused by the same circuit components.

The invention will be explained below with reference to the embodiments shown in the drawings.
In the drawings, the same reference numerals as in FIGS. 2 and 3 indicate the same or equivalent parts.

As is clear from the figure, the embodiment shown in Fig. 4 is similar to the embodiment shown in Figs.
By combining the circuits shown in the figure, the common parts of both circuits with a low failure rate are commonly used.

When the changeover switch 33 is turned on, the non-contact type device shown in FIG. 2 is operated, and when the changeover switch 33' is turned on, the contact type device shown in FIG. 3 is operated.

If configured as in the present invention, one suitable for regular use can be selected in a field test, the other can be used as a backup, and when the regular circuit breaks down, it can be immediately switched to the backup circuit.

With this configuration, it is possible to prevent recurrence of the same accident and provide a control device that is compatible with the system.

[Brief explanation of drawings]

Fig. 1 is a slip-torque characteristic curve diagram showing the specific power transition of an induction motor, Figs. 2 and 3 are circuit diagrams of a pumped storage starting device for a conventional direct-coupled induction motor-started pumped storage power plant, and Fig. 4 is FIG. 1 is a circuit diagram showing an embodiment of the present invention. The same reference numerals indicate the same or corresponding parts throughout each drawing, and 1
is the generator motor, 2 is its field winding, 3 is the induction motor,
Reference numeral 4 designates a secondary resistance for speed adjustment, 33 a changeover switch for a non-contact type starter, and 33' a changeover switch for a contact type starter.

Claims (1)

[Claims] 1. An operational amplifier that compares the primary current of the induction motor that starts the generator motor with a set value, and an armature current of the DC motor that adjusts the value of the secondary resistance of the induction motor according to the output of this operational amplifier. After the speed of the induction motor reaches a predetermined value,
a first automatic control device comprising a voltage setting device that applies a voltage to the operational amplifier according to the difference between the phase of the generated voltage of the generator motor and the phase of the voltage of the electric power system; a first relay that operates to flow a current in one direction to the DC motor; and a second relay that operates to flow a current in the opposite direction to the DC motor when the primary current is below a certain value.
relay and after the speed of the induction motor reaches a predetermined value,
a second automatic control device comprising a contact point for operating the first or second relay according to the difference between the phase of the generated voltage of the generator motor and the phase of the voltage of the electric power system; A backup system for an automatic control device that controls the speed of the induction motor by switching the automatic control device to either one.