JPS6116799Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device for operating a water turbine generator to adjust the water level.

Small and medium capacity run-of-river hydropower plants often perform water level adjustment operations that automatically adjust the output of the water turbine according to the upper water level. In this water level adjustment operation, the speed governor is released upward and the guide vanes of the water turbine are regulated by the load limiting mechanism, and when a positive or negative deviation occurs in the water tank water level, the water turbine's load limiting motor is activated. It is driven in reverse and opens and closes the guide vanes to adjust the amount of water flowing into the turbine.

FIG. 1 shows a control block of a conventional water level regulator. In the figure, the opening degree of the guide vane 2 operated by the load limiting electric motor 1 is detected by the detector 3, and the amount of water flowing into the water turbine 4 through the guide vane 2 is detected by the water level detector of the water tank 6 through the penstock 5. Detected at 7. The detection signals of detectors 3 and 7 are the set water level Hs
A comparison is made and the result is inputted to the deviation proportional ON-OFF controller 9 through the preamplifier 8, and the motor 1 is driven in the forward and reverse directions, that is, the opening degree of the guide vane 2 is adjusted in the direction in which the deviation becomes zero.

Now, if the water level in the water tank 6 rises, the water level adjustment device controls the amount of water flowing into the water wheel 4 to increase. Here, the water level adjustment has a characteristic called a water level adjustment rate as shown in FIG. 2, and when the guide vane 2 is controlled in the opening direction, the guide vane opening degree is adjusted to match the changed water level and the control is stopped.

In such water level adjustment, if the water tank capacity is sufficiently large and the speed of water level change is significantly smaller than the guide vane control speed, the control system will be sufficiently stable even with continuous control. However, if the water tank capacity is small or the penstock is long due to constraints such as geographical conditions, continuous control of the load limiting motor may result in overcontrol since changes in water level are an integral value of flow rate. The control system becomes unstable. Therefore, if the water tank capacity is small or there is a large delay in the water level pipe, intermittent control is used to reduce the control speed and perform control proportional to the deviation. However, when the water tank capacity becomes extremely low, it becomes difficult to stabilize the tank even with the above-mentioned intermittent control. For example, as shown in FIG. ₃ , when the deviation water level ΔH from the set water level H exceeds the dead zone h of the ON-OFF controller 9 due to an increase in the differential flow rate ΔQ between inflow and outflow to the water tank at time t0, By increasing the opening degree X of the guide vane 2, the water level rise rate starts to decrease, and then the water level stops rising and begins to fall. At this point _t1 , △Q becomes zero and equilibrium is achieved. However, since the water level is still sufficiently high, the guide vane is still controlled in the direction of opening, and the control amount C is overcontrolled in the shaded area.

As a device for improving such overcontrol, the inventors of the present invention have proposed a control method in which the rate of change in water level, that is, the amount ΔQ of increase or decrease in flow rate is also added to the feedback signal.

An object of the present invention is to provide a water level adjustment device that further improves control performance in a control device that uses feedback signals that include increases and decreases in flow rate.

FIG. 4 is a block diagram showing an embodiment of the present invention, and the same parts or parts having the same functions as those in FIG. 1 are designated by the same reference numerals. In Fig. 4, the water level change rate detector 10 detects the increase/decrease in flow rate ΔQ from the detection signal of the water level detector 7, and this detection signal is also compared with the set water level H along with the guide vane opening X and the water level H _F. (match) Furthermore, the sign determination circuit 11 determines whether ΔQ is positive or negative when ΔQ increases beyond the level set in the dead zone, and the sign determination circuit 12 determines whether ΔH is positive or negative. Then, when ΔQ is positive and ΔH is negative, or when ΔQ is negative and ΔH is positive, the relay 13 is activated to make the output of the preamplifier 8 zero to perform control lock. AND gates 14 and 15 and OR gate 16 form an operating condition circuit for relay 13.

According to such a control device, as shown in the waveforms of various parts in FIG. 5, by feeding back the difference △Q in flow rate, △Q becomes zero and balance is achieved at t ₁
Afterwards, the difference ΔQ is reversed, the increase in the guide vane opening degree X is suppressed, and overcontrol is suppressed, making it easier to maintain stability. Furthermore, when △Q becomes negative and larger than the value set in the dead band, a further increase command is issued if △H is positive, but relay 13 is activated since △Q<0, △H>0. Since ΔQ is negative, ΔH gradually decreases and settles at the set value H.
Conversely, when ΔQ is positive and ΔH is negative, control is also locked and overcontrol is suppressed.

As described above, the water level adjustment device according to the present invention is
Since the rate of change in water level is also incorporated into the control system and a control lock is applied to prevent overcontrol after the control system is balanced, it is possible to achieve more stable control of the system and to improve response speed and accuracy.

[Brief description of the drawings]

Figure 1 is a block diagram showing a conventional water level adjustment device, Figure 2 is a diagram for explaining the water level adjustment rate, Figure 3 is a diagram for explaining the control operation in Figure 1, and Figure 4 is a diagram for explaining the water level adjustment rate. FIG. 5 is a block diagram showing one embodiment of the invention, and is a diagram for explaining the control operation in FIG. 4. 1... Electric motor, 2... Guide vane, 3... Opening degree detector, 4... Water turbine, 5... Hydraulic pipe, 6...
Water tank, 7...Water level detector, 8...Preamplifier, 8
...ON-OFF regulator, 10... Water level change rate detector, 11, 12... Sign determination circuit, 13... Relay, 14, 15... AND gate, 16... OR gate.

Claims (1)

[Scope of utility model registration request] In a water level adjustment device that controls the opening of a guide vane by matching a detected value of the opening of the guide vane, a detected value of the water tank water level, and a detected value of the rate of change of the water tank water level to a set water level to operate a water turbine generator for water level adjustment, Determine the positive or negative sign of the water level change rate above, determine the positive or negative sign of the deviation water level from the set water level, and if the water level change rate is positive and the deviation water level is negative, or if the water level change rate is negative. A water level adjusting device characterized in that the device further comprises means for locking guide vane opening control when the deviation water level is positive.