JPS6129983Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electric speed governor that controls the rotational speed of a water turbine to be constant by opening and closing the guide vanes of a water turbine for power generation using an electric motor.

Conventionally, most speed governors for keeping the rotational speed of power generating water turbines constant have been mechanisms in which the guide vanes of the water turbines are controlled to open and close using hydraulic servometers.

On the other hand, there is a device that operates the guide vane using an electric motor, but this type of electric operating device only has the function of opening or closing the gate to a predetermined opening degree, and therefore the rotation of the water turbine cannot be controlled. It was never used as a speed governor to keep the number constant. Figures 1 and 2 show a worm gear type mechanism among this type of electric operating device, and as shown in both figures, a worm is connected to a gate shaft 1 for operating a guide vane connected to a gate link (not shown). A wheel 2 is attached to the shaft, and a worm 3 meshing with the worm wheel 2 is connected to a gear 4 for deceleration.
The opening of the guide vane (not shown) is detected using a pointer 7 fixed to the gate shaft 1 and a fixed scale plate 8. To open and close the guide vane, a switch (not shown) is provided near the gate shaft 1 that rotates the electric motor 6 in forward and reverse directions and stops it, and the operator operates this switch while looking at the pointer 7.
The opening degree is set by turning it ON/OFF. Therefore, the operator must go to the gate shaft 1 each time to perform opening/closing operations, which is extremely troublesome, and it is practically difficult to keep the rotational speed of the water turbine constant at all times with this operation. . In addition, the first and second
In the figure, 9 is the foundation, 10 is the bed, 11 is the gate shaft bracket, 12 is the worm bracket,
13 is a scale plate support metal fitting.

The purpose of the present invention is to provide an electric speed governor.The speed governor of the present invention uses an actuator that converts the rotational motion of an electric motor into linear motion using a mechanism using a ball screw and a ball nut. In addition to operating the guide vane, a control circuit is used to control the rotation of the electric motor by detecting the rotation speed of the water turbine in pulses, keeping the acceleration constant, and detecting the operating position of the actuator to quickly control the electric motor. This allows the rotation speed of the water turbine to be constant regardless of the load. The present invention will be described in detail below based on an embodiment shown in FIGS. 3 to 7 of the drawings.

FIG. 3 is a configuration diagram including a partial cross section of the actuator for operating the guide vane. In the figure, 14
Reference numeral 15 indicates a ball screw, and 15 indicates two ball nuts that are screwed together. Two ball nuts 15 are frame 1
6 Spacer 1 is placed inside the slide shaft 18 that slides on the inner circumference.
9 and is fitted using a ring key 20, and the slide shaft 1 is secured by a ball nut 15.
8 is designed to move back and forth. Reference numeral 21 denotes a reducer integrated with the upper electric motor 6. This reducer 21 is attached to the left side of the frame 16, and its output shaft 22 and the base end of the ball screw 14 are connected by coupling 2.
It is connected by 3. A slide head 24 whose outer periphery is threaded is fixed to the tip of the slide shaft 18, and a stopper 25 for adjusting the stroke,
26 is screwed on. A bracket 27 is attached to the right side of the frame 16 to serve as a stroke reference, and a position detector 28 such as a potentiometer or differential transformer is installed on the top of this bracket 27 to detect the slide position. The shaft 29 of the detector 28 and the slide head 24 are connected to the arm 3.
It is connected with 0. Further, one end of a coil spring 31 is connected to the frame 16 and the other end of the coil spring 31 is connected to the base end of the slide shaft 18 via a rod 32. Reference numeral 33 denotes a gate shaft arm pivotally attached to the upper end of the gate shaft 1, and the gate shaft arm 33 and the slide head 24 are connected by a connecting jig 34. In addition, in Figure 3, 35
is a bearing that pivotally supports the gate shaft 1. FIG. 4 shows the inside of the ball nut 15, where 36 is a ball and 37 is a cap. Furthermore, FIG. 5 shows the connecting portion between the actuator and the gate shaft 1 from above.

In such an actuator, when the electric motor 6 is rotated forward or backward, the ball screw 14 rotates forward or backward via the reduction gear 21, and the ball nut 15 and the slide shaft 1 are rotated forward or backward.
8 and the slide head 24 move linearly back and forth,
As a result, the gate shaft arm 33 connected via the connecting jig 34 rotates the gate shaft 1 in the opening or closing direction of the guide vane. In this case, the electric motor 6 is equipped with a brake, which is applied when the power is turned off. This is because the guide vanes themselves are normally designed to be biased in the closing direction, so in the unlikely event of a power failure, the actuator is returned by the force from the guide vane, causing the guide vane to automatically close. With conventional worm gear type electric operating devices, it is not possible to transmit power from the guide vane side,
When the power goes out, the guide vanes are locked. The maximum stroke of the guide vanes can be adjusted by adjusting the positions of the stoppers 25 and 26.
The impact when the stoppers 25, 26 hit the bracket 27 is absorbed and mitigated by the coil spring 31.

Next, FIGS. 6 and 7 show examples of control block diagrams for controlling the actuator of such a configuration and operation to keep the rotational speed of the water turbine constant. The control block diagrams in FIGS. 6 and 7 differ in whether the motor 6 in FIG. 3 is an induction motor 6a or a DC motor 6b, and the induction motor 6a is equipped with an inverter 38 and driven by a DC power source. By doing so, the same control circuit is created. Therefore, FIG. 6 will be explained below.

In Figure 6 (the same applies to Figure 7), 39
is a rotation speed setting device; 40, 41, 42 and 43 are first, second, third and fourth differential amplifiers; 44,
45 and 46 are first, second and third amplifiers,
47 is the actuator shown in FIG. 3, 48 is a water wheel, 49 is a pulse detector that detects the rotation speed of the water wheel 48 or the generator connected to the water wheel 48 by pulses, and 50 and 51 are the number of pulses per unit time. 52 is an acceleration conversion circuit that calculates the rate of change in the output of the F/V converter 51 and detects the acceleration of the rotation speed of the water turbine 48. This control system feeds back the opening degree of the guide vane, the rotation speed of the water turbine 48 or the generator, and the rotation speed of the electric motors 6a, 6b. The currents of the motors 6a, 6b are adaptively controlled by a minor loop in which the output of the position detector 28 is fed back via the fourth differential amplifier 43 to the third amplifier 46 that drives the motors 6a, 6b. A first differential amplifier 40 takes the difference between the output of the F/V converter and the output of the rotation speed setter 39 to form a feedback loop that keeps the rotation speed of the water turbine 48 constant. A second differential amplifier 41 calculates the difference between the output of The difference between the output of A feedback loop is constructed to stabilize the system.
That is, the rotation speed is detected as a pulse from the water turbine 48 by the pulse detector 49, and this is detected by the F/V converter 5.
After converting into a voltage value at 0.51, it is passed through a well-known differential, integral, and proportional circuit (not shown) to the rotation speed setting device 3.
By comparing with the set value from 9, if there is a difference between the set value and the actual rotation speed, the
The actuator is moved by driving the electric motors 6a and 6b at a desired speed using PID operation, and the rotation speed of the water turbine 48 is maintained at the set value by closing or opening the guide vane. In this case, since the acceleration is controlled to be constant, the rotational speed control in a transient state is stable.

As specifically explained above with the examples,
According to the speed governor of the present invention, since a hydraulic device is not required, the installation area is significantly smaller, maintenance is easier, and equipment cost is significantly lower. Furthermore, since the guide vanes are opened and closed by controlling the electric motor, a highly accurate speed governor can be easily obtained. This control uses constant acceleration control, so the system is stable.
Furthermore, since a ball screw mechanism is used as the actuator, power transmission is reversible, and the guide vane will not be locked even if the power is turned off.

[Brief description of the drawings]

1 and 2 are a plan view and a partially sectional side view of a conventional electric operating device used to open and close a guide vane. 3 to 7 relate to an embodiment of the present invention, FIG. 3 is a side view including a partial cross section of the actuator, FIG. 4 is an explanatory view of the inside of the ball nut, and FIG. 5 is a plan view of part A in FIG. 3. Figures 6 and 7
Each figure is a block diagram of the control circuit. In the drawing, 1 is a gate shaft, 6 is an electric motor, 6
a is an induction motor, 6b is a DC motor, 14 is a ball screw, 15 is a ball nut, 16 is a frame,
17 is a bearing, 18 is a slide shaft, 21 is a reduction gear,
24 is a slide head, 28 is a position detector, 33
is the gate shaft arm, 34 is the connection jig, 38
is the inverter, 39 is the rotation speed setting device, 40, 4
1, 42, 43 are differential amplifiers, 44, 45, 46
is an amplifier, 47 is an actuator, 48 is a water wheel,
49 is a pulse detector, 50 and 51 are frequency/voltage converters, and 52 is an acceleration conversion circuit.

Claims (1)

[Scope of utility model registration request] In a speed governor that uses an electric motor as the power source for opening and closing the guide vanes and controls the rotation of this electric motor to keep the rotation speed of the power generation water turbine constant, a ball screw is supported by a bearing in a frame and rotated by the electric motor. , a ball nut screwed with this ball screw,
a slide shaft integrally provided with the ball nut and slidably housed within the frame;
An actuator is composed of a connecting jig and a gate shaft arm that connect this slide shaft and a gate shaft for operating the guide vane, and a pulse detector that detects the rotation speed of the water turbine in pulses is added to the circuit that controls the electric motor. and a feedback loop including a converter that converts the number of pulses into voltage, and an acceleration conversion circuit that calculates the rate of change of the converter output, and also includes a position detector that detects the operating position of the actuator. A speed governor for a water turbine for power generation, characterized in that a loop is provided to feed back a detection signal of the governor.