JPH0731521B2 - Electric speed governor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a proportional / integral / derivative (PID) calculation type or a proportional / integral (PI) calculation type for adjusting speed and output of a water turbine in a hydroelectric power plant. The present invention relates to an electric speed governor.

[Conventional technology]

Conventionally, as this type of proportional / integral / differential operation type electric speed governor, one having a configuration shown in FIG. 4 is known. That is, in FIG. 4, reference numeral 10 is a speed setter, 12 is a speed detector, and 14 is a PID calculator. The speed detector 12 is for detecting the number of revolutions of the water turbine generator 16 by converting it into an electric signal, and performing a subtraction between the output signal of the speed setting device 10 and the detection signal of the speed detector 12 to obtain the speed. Deviation signal △
get f. The velocity deviation signal Δf thus obtained
Obtains a deviation signal from the output signal Δp of the speed droop rate calculator 18, inputs it to the PID calculator 14, performs PID calculation in this PID calculator 14, and outputs an appropriate servo motor opening command value. Is output. The output signal of this PID calculator 14 is compared with the output of the load limit setter 34 in the low value output circuit 32, and a low value is set so as not to exceed the load limit value and output as a servo motor opening command value. To do. Then, this servo motor opening command value controls the hydraulic system 26 via the opening adjuster 20, the actuator 22 and the servo motor 24 to appropriately control the output of the water turbine generator 16. In this case, the opening degree detector 28 detects the opening degree of the servo motor when the hydraulic motor opening / closing adjustment is performed by the servo motor 24.
Servo motor opening actual value obtained in step 1 and the PID calculator 14
It is set by inputting the deviation signal Δs from the servo motor opening command value obtained in step 2 to the opening controller 20. Therefore, the opening adjuster 20 outputs the opening adjustment signal Δs ′ proportional to the deviation signal Δs to control the actuator 22. The actuator 22 converts the opening adjustment signal .DELTA.s' into a mechanical deviation and performs an opening / closing operation by the servo motor 24. Then, by the opening / closing operation by the servo motor 24, the actual output frequency thereof rises or falls through the hydraulic system 26 and the water turbine generator 16. Further, the actual value of the servo motor opening obtained by the opening detector 28 is input to the speed droop rate calculator 18 as a deviation signal from the setting signal of the load setter 30, and the speed droop rate calculator 18 calculates the speed. The droop rate signal Δp is calculated.

However, the speed deviation signal Δf and the speed droop rate signal Δp gradually decrease as the output actual frequency thereof rises or falls through the hydraulic system 26 and the hydraulic turbine generator 16 by the opening / closing operation of the servo motor 24. Be adjusted. Therefore, the electric speed governor configured in this way is
The control operation is performed until the signals Δf and Δp become zero.

In the electric speed governor, the PID calculator 14 is
Those having a circuit configuration as shown in FIGS. 5 (a) to 5 (c) can be preferably used. That is, FIG. 5A shows a configuration in which the proportional calculator 36, the integral calculator 38, and the derivative calculator 40 are connected in parallel, and the outputs of the respective calculators are added. Further, the one shown in FIG. 5 (b) is composed of a differential calculator 40, an integral calculator 38, and a restoration differential calculator 42, and the output obtained by differentiating the input signal by the differential calculator 40 and the input signal It is configured such that when adding and inputting this to the integration calculator 38, the output of the integration calculator 38 is calculated as the deviation from the differential calculation output obtained through the restoration differentiation calculator 42 and integrated. is there. Further, the one shown in FIG. 5 (c) is composed of a differential calculator 40 and a proportional / integral calculator 44,
The output of the input signal is differentiated by the differential calculator 40 and the input signal are added, and the proportional / integral calculator 44 performs proportional / integral calculation.

[Problems to be solved by the invention]

In the control operation of the above-described conventional electric speed governor, since the speed deviation signal Δf is about 100% when the main engine is started, the load limit setter 34 is set at a preset position (starting opening).
When the signal Δf reaches approximately zero, speed control by the PID calculator 14 is performed to prevent overcontrol and shorten the speed-up time.

However, the output of the PID calculator 14 decreases only after the speed deviation signal Δf turns negative, so the speed overshoots due to the inertia of the water turbine generator 16.
Conventionally, as a measure against this type of overshoot, the output of the load limit setter 34 is switched in multiple stages, for example, the PID calculator 14
The method of limiting the output of the integral calculator (indicated by the broken line) is adopted, but in either case, strictly speaking, in the case of the PID governor, the above is due to the effect of the differential calculator when the signal Δf reaches minus. Just before the signal Δf becomes negative, the output of the PID calculator 14 decreases, so that an overshoot of the speed cannot be avoided.

Further, in general, when the effective head changes, the starting opening is constant, so the flow rate becomes constant, so the output of the water turbine that is the product of the effective head and the flow rate changes. Therefore,
When the effective head increases, the amount of overshoot of the speed also increases, the control response deteriorates, the time until reaching the steady state is extended, and the time until the synchronization is input becomes long.

Therefore, an object of the present invention is to control the speed overshoot amount at the time of starting the main engine to be substantially zero, and to control so that the time until synchronization is made short, and to maintain such a control function even if the effective head changes. An object of the present invention is to provide an electric speed governor capable of performing the above.

[Means for solving problems]

The electric speed governor according to the present invention inputs the deviation signal between the set output of the speed setter and the detected output of the water turbine generator to perform the PID calculation or the PI calculation, and the opening degree based on the obtained calculation output. In an electric speed governor equipped with an opening adjustment loop that follows and controls the servomotor that opens and closes the hydraulic system via the controller and actuator, at the time of starting the main engine, the rotation speed of the main engine is the set value of the speed setter. When it reaches, a speed set value smaller than the set value of the speed setter set in the startup speed setter is output as an exponential function via an exponential function unit, and this output signal is output to the speed setter. It is characterized in that it is configured to add.

[Action]

According to the electric speed governor according to the present invention, at the time of starting the main engine, that is, when increasing the speed 100% from the zero speed of stop to the rated speed, the conventional speed setter provides a fixed output of the starting speed setter. The output that changes exponentially is added from an appropriate point in time, the target design value for control is changed appropriately, and the control system is made to follow this, so that the overshoot of the output deviation becomes almost zero, and this response speed It will be possible to shorten the time required for the synchronization of the main engine by improving the. Such operation characteristics can be surely maintained not only at the time of general startup, but also when the effective head at startup varies.

〔Example〕

Next, an embodiment of an electric speed governor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a system diagram showing an embodiment of an electric speed governor according to the present invention. Note that in FIG. 1, for convenience of explanation, the same components as those of the conventional component shown in FIG.
The same reference numerals are given and detailed description thereof is omitted. That is, in the present invention, the start-up speed setter 50, the exponential function unit 52 that operates by the addition start signal S _A generated after the number of revolutions of the main engine reaches the set value by the speed setter 10, and the adder 54 And is provided. Other configurations are the same as those of the conventional device shown in FIG.

Therefore, the startup speed setter 50 is configured similarly to the speed setter 10, and the speed set value is set to 30% of the rated speed.
Set to a degree. Normally, the speed setting range of the speed setting device 10 is 90 to 110% of the rated speed, but in the present invention, 60 to 80% to add the speed setting value 30% of the starting speed setting device 50. As a result, the speed setting value (fs) is set to 90
It is set to ~ 110%. Therefore, the exponential function unit 52 operates by the addition start signal S _A generated after the number of revolutions of the main engine reaches the set value of the speed setting unit 10 described above, and the set value of the starting speed setting unit 50 is set to an exponential function. The output is performed and the adder 54 operates so as to be added to the set value output of the speed setter 10.

Therefore, the output characteristics of the adder 54 are as shown in FIG. In FIG. 2, the horizontal axis represents the elapsed time t, and the vertical axis represents the speed setting value fs which is the output of the adder 54.
At the time of starting the main engine, it is operated at the speed setting value f ₁ of the speed setter 10, and at the time t ₁ when the number of revolutions of the main engine reaches this setting value f ₁ ,
An addition start signal S _A is generated, which causes the exponential function unit 54 to operate and reach the set value f ₂ of the starting speed setter 50 by a temporary delay function.

According to the present invention, based on the speed setting value fs, the PID calculator 14, the low value output circuit 32, the opening adjuster 20, the actuator 2
2, the servo motor for opening and closing the hydraulic system can be appropriately tracked and controlled by the opening adjustment loop including the servo motor 24, the opening detector 28, and the like.

〔The invention's effect〕

As is apparent from the above-mentioned embodiments, according to the present invention,
A speed setter for start-up is provided, and when the number of revolutions of the main machine reaches the set value based on the set value by the conventional speed setter, the set value of the start-up speed setter is output as an exponential function. Is configured to be added to the output signal of the speed setter, the amount of speed overshoot becomes approximately zero,
The time to final stabilization can be shortened. Also, since there is no overshoot for the speed setting value, the final speed setting value fs at the time of starting the main engine can be easily set to 100%, and the time until the synchronization is made can be greatly shortened. Further, the effect can be effectively maintained even when the effective head changes.

Therefore, the starting characteristics of the electric speed governor according to the present invention will be described in comparison with the case of the conventional device. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b) show the starting characteristics of the conventional device, with the horizontal axis representing time (seconds),
Speed is shown on the vertical axis (% deviation from rated speed is shown by the solid line)
And the servo motor opening (% is shown by a broken line) are set respectively. FIG. 6 (a) shows a general starting characteristic. In this case, it is confirmed that the overshoot amount of the speed curve increases. FIG. 6 (b) shows a starting characteristic when the set value of the load limit setter 34 is controlled in two stages in order to reduce the amount of overshoot. In this case, the time to reach the rated speed becomes relatively long even if the amount of overshoot decreases. FIG. 7 (a) shows a starting characteristic when the limiting function by the load limit setting unit 34 is added to the integral computing unit of the PID computing unit 14. In this case, the overshoot amount is smaller than the characteristics shown in FIGS. 6 (a) and 6 (b),
Since the servo motor opening is closed after the output deviation Δf reaches a substantially negative value, an overshoot of several% cannot be avoided. Further, FIG. 6 (b) shows the starting characteristic when the effective head is increased by 20% under the same starting condition as the characteristic shown in FIG. 6 (a). In this case, the amount of overshoot is larger than that of the characteristic shown in FIG.

On the other hand, FIGS. 3 (a) and 3 (b) show the starting characteristics by the device of the present invention, and the condition setting of the horizontal axis and the vertical axis is the same as above. FIG. 3 (a) shows the starting characteristics when the speed set value of the starting speed setter 50 is set to 30% and the operating time of the exponential function unit 52 is set to 8 seconds. In this case, there is no overshoot, and the time to reach the rated speed is shortened compared to the conventional starting characteristic. Further, FIG. 3 (b) shows the starting characteristic when the effective head is increased by 20% under the same starting condition as the characteristic shown in FIG. 3 (a). Also in this case, FIG. 3 (a)
It was confirmed that almost the same characteristics as shown in (3) did not occur, and the time to reach the rated speed could be kept short.

As is clear from the comparison of the start-up characteristics described above, according to the device of the present invention, regardless of the fluctuation of the effective head, it is easy to put the turbine generator into the synchronous speed in a short time after starting the main engine. Benefits are obtained.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of an electric speed governor according to the present invention, and FIG. 2 is an explanatory view showing a change state of a speed set value fs by the electric speed governor shown in FIG. Figure 3 (a),
(B) is a characteristic curve diagram when the effective heads of the speed and the servo motor opening of the electric speed governor according to the present invention are different, FIG. 4 is a system diagram of a conventional electric speed governor, and FIG. (A)-(c) are block connection diagrams showing various configuration examples of the PID calculator shown in FIG. 4, and FIGS. 6 (a), (b) and FIGS. 7 (a), (b) are respectively shown. It is a characteristic curve figure of speed and a servo motor opening of the conventional electric type speed governor. 10 …… Speed setter, 12 …… Speed detector 14 …… PID calculator, 16 …… Water turbine generator 18 …… Speed droop rate calculator, 20 …… Opening regulator 22 …… Actuator, 24 …… Servo motor 26 …… Opening detector, 28 …… Hydraulic system 30 …… Load setter, 32 …… Low value output circuit 34 …… Load limit setter, 36 …… Proportional calculator 38 …… Integral calculator, 40: Derivative calculator 42: Restoration differential calculator 44: Proportional / integral calculator 50: Startup speed setter, 52: Exponential function unit 54: Adder

Claims (1)

[Claims] 1. A PID calculation or a PI calculation is performed by inputting a deviation signal between the set output of the speed setting device and the detected output of the water turbine generator, and the PID calculation or the PI calculation is performed. In an electric speed governor equipped with an opening adjustment loop that follows and controls the servomotor that opens and closes the hydraulic system, it is started when the speed of the main machine reaches the set value of the speed setter when the main machine starts. A speed set value smaller than the set value of the speed setter set for the speed setter is output as an exponential function via an exponential function unit, and this output signal is added to the output signal of the speed setter. An electric speed governor characterized in that.