JPS6130155B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric speed governor for a water turbine.

Figure 1 shows a block diagram of a conventional electric governor for water turbines. The rotation speed n of the main engine (water turbine) 6 is detected by the rotation speed detector 1 as the actual rotation speed N, and is compared with the target rotation speed N ₀ set in the target rotation speed setting device 3 by the rotation speed deviation detection circuit 2. . Then, the rotational speed deviation is determined, and an adjustment signal α for the flow rate control valve 5 based on the deviation is obtained. This adjustment signal α is amplified by the amplifier circuit 4 and becomes a control signal a to the flow rate control valve 5. The flow rate control valve 5 is controlled based on the control signal a, and its opening degree g is controlled so that the deviation in rotational speed becomes zero.

Such conventional electric speed governors for water turbines do not have any problems in controlling the main engine 6 during normal operation, but when a load or disconnection occurs and the main engine has to be stopped, the response becomes difficult. This is a problem because it is slow.

FIG. 2 is a flowchart showing the operation of a conventional electric speed governor for a water turbine when a load failure occurs at time _t0 . Assuming that a load failure occurs at time t ₀ , due to the delay of the rotation speed detection circuit 1, the rotation speed deviation is detected by the rotation speed deviation detection circuit 2 after the rotation speed has actually changed, and the adjustment signal α is will be output, so there will be a delay time △t in the operation.
occurs. As a result, a delay time Δt also occurred in the operation of the flow rate control valve 5. In addition, since the rotational speed n of the main engine 6 gradually increases after the load or break occurs, there is a delay in the operation of the flow rate control valve 5 due to this effect. As a result, the peak value of the increase in rotation of the main engine 6 was also increasing.

The present invention provides a preceding signal to the flow control valve that precedes the adjustment signal of the flow control valve due to the rotational speed deviation when the load is cut off, thereby giving quick response to the operation of the flow control valve and suppressing the rise in main engine rotation to a small level. The purpose is to obtain an electric speed governor for water turbines.

FIG. 3 shows a block diagram of an embodiment of the present invention. In FIG. 3, a rotation speed detection circuit 1, a rotation speed deviation detection circuit 2, a target rotation speed setting device 3, an amplifier circuit 4, a flow rate control valve 5, and a main engine 6 are the same devices as those in FIG. The no-load opening setting device 7 is the no-load opening.
This is to set G ₀ . An opening degree detection circuit 8 of the flow rate control valve 5 works in conjunction with the flow rate control valve 5 to generate an actual opening degree G that is proportional to its opening degree g. The opening deviation detection circuit 9 detects the difference between the no-load opening G ₀ of the flow control valve 5 given by the no-load opening setting device 7 and the opening detection circuit 8 and the actual opening G of the flow control valve 5. That is, the opening degree deviation signal β of the flow rate control valve 5 is output. The deviation signal β of the opening degree deviation detection circuit 9 is transmitted to the flow rate control valve 5 by adjusting the gain with an amplifier circuit 10 that can vary the gain.
amplify the opening deviation signal β. and opening deviation β
Obtain the adjustment signal α' of the flow control valve by . The switch circuit 11 is a contact point that closes at the same time as the load is cut off, and opens when the flow rate control valve 5 reaches the no-load opening _G0 . Only while the contact of this switch circuit 11 is closed, the adjustment signal α' is generated based on the opening deviation of the flow rate control valve 5.
is given to the priority circuit 12. The priority circuit 12 selects and outputs the larger one of the adjustment signal α based on the given rotational speed deviation and the adjustment signal α' based on the opening degree deviation in order to drive the flow rate control valve 5 in the closing direction. . That is, the priority circuit 12 provides the amplifier circuit 4 with an adjustment signal F which is larger in the closing direction of the adjustment signal α and the adjustment signal α'. This increases the speed governor's responsiveness.

Next, the operation will be explained with reference to FIG. Before the load is interrupted, the main engine 6 has a generator load, so the flow rate control valve 5 is opened more than the no-load opening according to the load. Therefore, the adjustment signal α' from the amplifier circuit 10 is a signal that attempts to close the flow rate control valve 5 by that amount. When the contact of the switch circuit 11 closes at the same time as the load is disconnected, the adjustment signal α' is applied to the priority circuit 12.
Immediately after the load is disconnected, the rotation increase is still small, so the adjustment signal α' is larger in the direction of closing the flow control valve 5 than the adjustment signal α, so the adjustment signal α' is used as the adjustment signal F of the priority circuit 12. coming out. In other words, this adjustment signal α' is used as the adjustment signal F in the amplifier circuit 4.
is given to operate the flow control valve 5.

As a result, unlike the conventional system in which the flow rate control valve 5 is operated after the rotation starts to increase, in the present invention, the adjustment signal α' is given in advance before the rotation starts to increase, so that the operation of the flow rate control valve 5 is delayed. , that is,
The delay time Δt shown in FIG. 2 disappears. This makes it possible to reduce the increase in rotation of the main engine 6. The broken line in FIG. 4 shows the characteristics in the conventional case.

Since the electric speed governor of the present invention generates the adjustment signal α' based on the flow control valve opening deviation by comparing the no-load opening G ₀ and the actual flow control valve opening G, the rotation speed detection circuit 1 Even in the event of a malfunction in the speed regulating function due to a malfunction in the rotational speed deviation detection circuit 2, etc., the flow control valve can be reliably closed to the no-load opening degree. Moreover, since the increase in the main engine rotational speed can be suppressed to a small level, overspeed can be prevented.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional electric speed governor.
FIG. 2 is an operating time chart of the same block diagram, FIG. 3 is a block diagram of an embodiment of the electric speed governor according to the present invention, and FIG. 4 is an operating time chart of the same embodiment. 1... Rotation speed detection circuit, 2... Rotation speed deviation detection circuit, 3... Target rotation speed setting device, 5... Flow rate control valve, 6... Main engine (water turbine), 7... No-load opening setting device , 8...Opening degree detection circuit, 9...Opening degree deviation detection circuit, 11...Switch circuit, 12...Priority circuit.

Claims (1)

[Claims] 1. A rotation speed deviation detection circuit that calculates the rotation speed deviation between the actual rotation speed of the water turbine and the target rotation speed and outputs an adjustment signal for the flow control valve based on the rotation speed deviation, and a an opening deviation detection circuit that calculates an opening deviation from the opening deviation and outputs an adjustment signal for the flow rate control valve based on the opening deviation, and closes when the water turbine is loaded or disconnected to pass the opening deviation adjustment signal. selects and outputs the one that increases the drive amount of the flow rate control valve in the closing direction from among an adjustment signal based on the opening degree deviation and an adjustment signal based on the rotation speed deviation obtained through this switch circuit. An electric speed governor for a water turbine, comprising a priority circuit and an amplifier circuit that outputs a control signal for the flow rate control valve based on an adjustment signal selected by the priority circuit.