JPS6189985A - Controlling method of deflector in discharge operation of pelton wheel - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a reversible phenomenon in a turbine as well as to aim at miniaturization of a turbine brake, by regulating opening of a deflector according of a needle, while avoiding a collision of the jet deflected by the deflector to a bucket, in time of discharge operation CONSTITUTION:In time of discharge operation, a select switch 19 from generating operation to this discharge operation and vice versa is connected to a contact (b), and a signal out of a needle opening detector 16 and a signal out of an electric governor 13 are inputted into a needle-deflector tracking device 20b in time of this discharge operation, thus signal processing takes place. These signals are converted into a control signal at a converter 21, through which a deflector distributing valve 22, and according to the opening, a deflector servomotor 10 is controlled. And, a full-open position of a water receiving surface of a deflector 9 is changed according to opening of a needle 7 in time of the discharge operation of the deflector 9, namely, a diameter (d) theta of a jet 3. With this constitution, the jet sprayed out of a nozzle 2 is deflected so as not to hit a bucket after colliding with the deflector 9 so that a reversible phenomenon in a turbine runner is made preventable.

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a method for controlling a deflector during discharge operation of a Pelton water turbine, and in particular, to prevent the jet ejected from the nozzle from completely hitting the bucket during discharge operation of a Pelton water turbine. The present invention relates to a deflector control method in discharge operation of a Pelton turbine.

(b) Prior art Pelton turbines are generally applied to high head and low flow locations, and horizontal shaft type is used for small capacity ones, and vertical shaft type is used for medium or large capacity ones. has been done. The structure and operation of this small capacity horizontal shaft type Pelton water turbine will be explained with reference to FIG. First, the pressure water introduced into the inlet curved pipe 1 is pressurized by the nozzle 2, becomes a high-speed jet 3, and hits the bucket 5 attached to the outer periphery of the runner 4.
After applying water power to do work, it is discharged into the lower discharge channel 6. During normal operation, the needle 7 in the nozzle 2 is opened and closed according to the load by a needle servo motor 8 to adjust the flow rate. Further, there is a deflector 9 between the nozzle 2 and the bucket 5, and when the load suddenly decreases, the deflector 9 is rapidly rotated by a deflector servo motor 10 to temporarily divert the direction of the jet 3 from the direction of the bucket 5. During this time, the needle 7 is gradually closed to control the rotational speed of the water wheel while suppressing an increase in water pressure due to the water hammer action in the penstock pipe 11. Furthermore, by fully closing the deflector 9, the direction of the jet 3 is deviated from the bucket 5, so the water turbine can be stopped suddenly, and furthermore, water can be continued to be discharged even when the water turbine is stopped.

In this way, compared to Francis turbines, Pelton turbines (a) can be operated by switching the number of nozzles depending on the load, resulting in high partial load efficiency; (b) runner inspection and replacement are easy, and the mechanism is Since this is simple, it is easy to replace parts worn and corroded by earth and sand, and (c) the use of the deflector 9 and jet brake has advantages such as a small increase in speed and water pressure.

Further, as for the deflector 9 of the Pelton turbine, there are two types: an inner hook type in which the water receiving part of the deflector enters from the side near the jet runner, and an outer hook type on the contrary. As a deflector of this type, a structure shown in FIG. 6 is generally known. FIG. 6 shows an enlarged view of the main parts during operation of the water turbine with the deflector opened. 2 is the nozzle, 3 is the jet, 7 is the needle, 9 is the deflector, and 9a is the pivot pin of the deflector 9.

In such a structure, the opening degree of the needle 7 is large,
Diameter d of jet 3. is large, when the deflector 9 is positioned in the traveling direction of the jet 3 as shown in FIG.
As shown in hydraulics, the part 3a of the jet 3 that is deflected from the direction inevitably flows out from the rear end of the deflector 9 with a velocity component in the reverse direction of the runner 4 and collides with the back surface of the bucket 5. Resulting in. Due to the force of the jet 3a colliding with the back surface of the bucket 5, the runner 4 is reversed.

This poses a risk of damaging the bearing metal.

In order to prevent this reversal, as shown in FIG. 8, the fully closed position of the deflector 9 is changed to increase the distance y between the tip of the water receiving surface 9b of the deflector and the center line 3C of the jet 3. When set to the + (plus) side, the jet 3a from the rear end of the water receiving portion 9b of the deflector A 9 will not collide with the runner 4. However, as shown in FIG. 9, the distance My can be changed by changing the opening degree of the deflector 9. When set to the + side, if the opening degree of the needle 7 is decreased, the jet 3 will not hit the deflector 9 and the jet 3 will not be able to be deflected.

Therefore, the jet 3b collides with the bucket 5 and the runner 4
Rotate in the forward direction. In this case, since the runner 4 rotates at a low speed, there is a risk of damaging the bearing metal of the runner 4.

In order to eliminate this drawback, the water receiving portion 9b of the deflector 9 should be made larger by the portion 9c shown by the dotted line, as shown in Fig. 6, that is, the opening angle θ from the center should be made larger. This is an impossible method because the nozzle 2 must be shaved by the length of the portion 9c shown by the dotted line, which reduces the strength of the nozzle 2.

Therefore, conventionally, torque is generated in the runner 4 in the opposite direction or in the forward direction depending on the opening degree of the needle 7 of the nozzle 2.
A brake with a large braking force to overcome this torque had to be installed on the water wheel or generator.

FIG. 10 shows a block diagram of a conventional control circuit that controls the opening degree of the needle 7 and the position of the deflector 9. The opening degree of the needle 7 is detected by a needle opening degree detector 12,
This detection signal is converted into a control signal by the converter 14 together with an electric signal corresponding to the rotational speed of the runner 4 from the electric governor 13, which controls the needle pressure regulating valve 15 and drives the needle servo motor 8 to adjust the opening of the needle 7. is controlled to a predetermined value.

On the other hand, the position of the deflector 9 is detected by the deflator opening detector 16, and is converted into a control signal by the converter 17 together with an electric signal corresponding to the rotational speed of the runner 4 from the electric governor 13, which controls the deflector pressure distribution valve I8. A deflector servo motor 10 is driven to control the position of the deflector 9 to a fully open position or a fully open position depending on whether the runner 4 is rotating or stopped.

In this way, in the conventional Pelton water turbine, the opening degree of the needle 7 and the position of the deflector 9 are controlled independently of each other, so torque is generated in the runner 4 in the opposite direction or in the forward direction, so the braking force that overcomes this torque is required. (c) Problems to be Solved by the Invention As described above, in the discharge operation of a Pelton turbine, a deflector with a small opening angle θ from the center is used. When the jet is deflected, if the diameter of the jet is reduced by changing the opening degree of the needle without changing the position of the deflector, the jet will no longer be deflected by the deflector.

(d) Purpose of the invention The present invention has been made in view of the above drawbacks.

The purpose of this is to use a narrow deflector with a small opening angle θ from the center of the deflector to prevent the jet flow from colliding with the bucket even when the jet diameter changes by changing the opening degree of the needle. Therefore, it is an object of the present invention to provide a method for controlling a deflector in discharge operation of a Pelton water turbine in which the runner is not rotated.

(e) Structure of the Invention In order to achieve the above object, the present invention is provided by rotatably provided on the front surface of a nozzle, by colliding a jet ejected from the nozzle and diverting the traveling direction of the jet from the runner. An internal deflector for performing discharge operation by stopping a Pelton turbine, the opening degree of the deflector being adjusted according to the opening degree of the needle so that the jet deflected by the deflector does not collide with the bucket. It is characterized by The configuration will be described below based on embodiments of the present invention.

(F) Embodiment FIGS. 1 and 2 are enlarged views of main parts of a deflector for a Pelton water turbine according to the present invention. The deflector 9 is rotatably attached to the nozzle 2 by a pin 9a, and is equipped with a hydraulic mechanism and a spring (not shown). It is configured so that it can be opened and closed. In addition, Fig. 1 shows that the distance between the tip 9b of the deflector's water receiving surface and the center line 3c of the jet is +yo (plus side), and the needle opening is large, that is, when the jet diameter is large, the deflector does not generate torque. In Fig. 2, the distance between the tip 9b of the water receiving surface of the deflector and the center line 3C of the jet is -yo (minus side), and the needle opening is small, that is, the diameter of the jet is It shows the opening degree of the deflector at which no torque is generated when it is small.

FIG. 3 shows a block diagram of a control device for controlling the opening degree of the needle and the position of the deflector according to one embodiment of the present invention. The detection signal is converted into a control signal by the converter 14 along with an electric signal corresponding to the rotational speed of the runner 4 from the electric governor 13, which controls the needle pressure regulating valve 15 and drives the needle servo motor 8 to control the opening of the needle 7. It is controlled to a predetermined value.

On the other hand, the output of the electric governor 13 is input to the changeover switch 19 between power generation operation and discharge operation.
During discharge operation, it is connected to the contact point.

During power generation operation, signals from the needle opening detector 12 and deflector opening detector 16 and signals from the electric governor 13 are transmitted to the needle deflector tracking device 20a during power generation operation.
The signal is input to the converter 21 and processed, and the signal is sent to the converter 21
is converted into a control signal, and the deflector pressure distribution valve 22 is controlled. The deflector servo motor 10 is controlled according to the opening degree of the deflector pressure distribution valve 22, and the deflector 9 is controlled according to the opening degree of the needle 7 during power generation operation.

In addition, during the discharge operation, the changeover switch 19 between the power generation operation and the discharge operation is connected to the contact point, and the needle opening degree detector 1 is connected to the needle deflector tracking device 20b during the discharge operation.
2 and the deflector opening detector 16, and the signal from the electric governor 13 are input and processed, and the signals are converted into control signals by the converter 21, and the deflector pressure distribution valve 22 is controlled.

The deflector servo motor 10 is controlled according to the opening degree of the deflector pressure distribution valve 22, and the deflector 9 is controlled according to the opening degree of the needle 7 during the discharge operation.

That is, as shown in FIG. 1, when the opening degree of the needle 7 is large and the diameter of the jet 3 is large, the distance between the tip 9b of the water receiving surface of the deflector and the center line 3c of the jet should be set to +yo. This can prevent the jet 3 ejected from the nozzle 2 from hitting the bucket after colliding with the deflector. Also, as shown in Figure 2, the jet 3
If the diameter of the deflector is small, the tip 9b of the water receiving surface of the deflector
By setting the distance between the center g3c and the jet center g3c to -y0, it is possible to avoid the jet 3 ejected from the nozzle 2 from directly hitting the bucket without colliding with the deflector.

In this way, the opening degree of the deflector 9 is determined by the opening degree of the needle 7 during discharge operation, that is, the opening degree of the jet 3. Since the fully open position of the water receiving surface of the deflector 9 is changed according to the
The jet 3 ejected from the nozzle 2 must collide with the deflector and then be deflected so as not to hit the bucket, thereby preventing the forward/reversal phenomenon of the water turbine runner 46. Note that FIG. This shows the relationship between the runner torque and the needle opening using the fully open position of the deflector as a parameter.If the distance between the tip of the deflector's water receiving surface and the center line of the jet is -y0, that is, the tip of the deflector's water receiving surface is When the water wheel protrudes below the center line of the jet, the water turbine torque is zero in the range where the needle opening is small (as shown in Figure 1), but as the needle opening becomes large, the reverse torque is generated. working (state shown in Figure 7). On the other hand, if you change the fully open position of the deflector and set the above distance to +yo, that is, if the tip of the water receiving surface of the deflector is above the center line of the jet, the turbine torque will decrease in the range where the needle opening is large. It is zero (state shown in FIG. 8), indicating that positive torque acts on the runner in a region where the needle opening degree is small (state shown in FIG. 9). Utilizing this characteristic, by changing the position of the deflector according to the needle opening degree, that is, when the needle opening degree is small, the distance between the tip of the water receiving surface of the deflector and the center line of the jet is -y. When the needle opening is large, by controlling the distance between the tip of the water receiving surface of the deflector and the center line of the jet to +yo, torque is applied to the runner in both forward and reverse directions over the entire needle opening range. but
It is possible to perform control so that no one occurs.

(g) Effects As is clear from the above explanation, the present invention can control the opening of the deflector used when stopping the water turbine according to the opening of the needle, without weakening the nozzle strength. During discharge operation of a Pelton turbine, the jet ejected from the nozzle can avoid hitting the bucket after colliding with the deflector, and the forward and reverse phenomenon of the turbine runner can be prevented, so the brake of the turbine can be downsized and costs can be reduced. Figures 1 and 2 are enlarged views of essential parts of a deflector of a Pelton turbine according to an embodiment of the present invention, and Figure 3 is an enlarged view of a needle opening according to an embodiment of the present invention. Figure 4 is a diagram showing the relationship between the runner torque and the needle opening with the fully closed position of the deflector as a parameter. Figure 5 is a block diagram of the control device that controls the deflector position and deflector position. Figure 6 shows the structure of the water turbine. Figure 6 is an enlarged view of the main part showing the position of the deflector during load operation of the turbine. Figure 7 is an enlarged view of the main part showing the deflector in the fully closed position. Figure 8 is during discharge operation. An enlarged view of the main part showing the deflector opening when the needle opening is large and no torque is generated. Figure 9 is an enlarged view of the main part showing the deflector opening when the needle opening is small and torque is generated in the positive direction during discharge operation. FIG. 10 is a block diagram of a conventional control circuit that controls the opening degree of the needle and the position of the deflector.

2... Nozzle, 3... Jet, 3a... Flow in the reverse rotation direction of the jet runner, 3b... Flow in the forward rotation direction of the jet runner, 3c... Center line of the jet, 4
... Runner, 7... Needle, 9... Deflector, 9a... Pin, 9b... Water receiving surface of deflector.

Figure 8 /

Claims (1)

[Claims] An internal deflector that is rotatably provided in front of a nozzle and causes a jet ejected from the nozzle to collide with the runner to divert the traveling direction of the jet from the runner, thereby stopping a Pelton turbine and performing a discharge operation, A method for controlling a deflector in discharge operation of a Pelton water turbine, comprising adjusting the opening degree of the deflector according to the opening degree of the needle so that the jet deflected by the deflection does not collide with a bucket.