JPS6316172A - Operation control method for reversible pump-turbine - Google Patents

Abstract

PURPOSE:To expand an operating range, by finding a variable to be expressed in the specified relational expression from the net pump head and rotational speed of a reversible pump-turbine and, when this variable goes beyond both upper and lower limit values of the operating range, changing a direction of prerotation. CONSTITUTION:A prerotation generator 6 is installed in an end at the side of a runner 3 of a suction pipe elbow 2. This generator 6 is driven by output of an arithmetic unit 11. The rotational speed detected by a rotational speed detector 9 is inputted into the arithmetic unit 11 together with the net pump head H detected by a net pump head detector 10 and thereby a variable H/N<2> is calculated. When this variable H/N<2> is more than the upper limit value of an operating range, prerotation in the same direction as a rotational direction of the runner is generated, but when the variable H/N<2> is less than the lower limit value of the operating range, the prerotation in the opposite direction is generated the other way. Accordingly, if exceeding the operating range of a reversible pump-turbine, its performance is maintainable.

Description

[Detailed Description of the Invention] (Objective of the Invention) (Industrial Application Field) The present invention relates to a method of controlling the operation of a pump-turbine, and particularly relates to a method of controlling the operation of a pump-turbine that expands the operating range of the pump-turbine. .

(Prior art) In general, the operating range of a pump-turbine is expressed as the range of the variable H/N2, where the total head is H1 and the rotational speed is N. Moreover, the range of this variable 1-1/N2 is determined at the time of designing the pump-turbine. It ends up. This is due to the following reasons.

FIG. 5 shows a velocity triangle diagram at the inlet of the runner blade 21, and FIG. 6 shows a pump characteristic diagram when the rotational speed is constant. Normally, the pump water wheel has a circumferential speed U. The absolute speed of the runner blade 21 is
. water has a relative velocity W. , an inlet angle β that coincides with the inlet angle β of the runner vane 21. δ1 is set so that the inflow occurs at .delta.1. However, as the total lift height T1 increases, the pumped water amount Q decreases, so the absolute speed of water becomes small to ■1, and as a result, the inflow angle β1 of water flowing into the runner blade 21 at a relative speed W
becomes smaller than the above-mentioned inlet angle β, and peeling occurs on the back side of the runner blade 21, reducing the efficiency of the pump-turbine and causing noise.
Shooting may occur and cause erosion. On the other hand, when the total head H decreases, the pumped water faQ increases and the absolute velocity of the water becomes large to ■2, so the inflow angle β2 of the water flowing into the runner blade 21 at the relative velocity W2 becomes larger than the above-mentioned population angle β. , peeling may occur on the front side of the runner blade 21. In addition, since the rotational speed N is almost directly proportional to the pumped water WQ except in the reverse region, when the rotational speed N reaches an upper limit, the runner blade 21
When the rotational speed N decreases, peeling may occur on the back side of the runner blade 21, similar to when the pumped water amount Q decreases.

For this reason, the operating range of the pump-turbine must be designed within a range in which separation does not occur at the inlet of the launch vane 21, and the range of the variable H/N2 is also inevitably determined.

By the way, in recent years [FM of a pumped storage power plant equipped with a pump-turbine]
For dynamic operation and agile operation of power systems, it is required to efficiently adjust the shaft input of pump-turbines during pumping operation with wide joints, and a method for adjusting the shaft input of such pump-turbines is required. As a solution, it is being considered to change the rotational speed or give a pre-swirl to the water flow passing through the suction side pipe.

(Problem to be solved by the invention) However, as mentioned above, the range of the variable H/N'', which is the operating range of the pump-turbine, is fixed.
If the change in the total head exceeds this range, the performance of the pump-turbine cannot be maintained, and if the shaft input of the pump-turbine is adjusted by changing the rotation speed, the rotation speed will change beyond the range of the variable H/N2. This is a safety hazard for the equipment. For this reason, when the total head is determined, the controllable rotational speed range is automatically determined, and the shaft input adjustment range is determined to be approximately proportional to the cube of this rotational speed. There was a problem in that it could not be adjusted over a wide range.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology, maintain the performance of a pump-turbine at and beyond the lower limit of the operating range of the pump-turbine determined at the design stage, and maintain the performance of the pump-turbine during pumping operation. An object of the present invention is to provide a method for controlling the operation of a pump-turbine by expanding the adjustment range of the shaft input of the pump-turbine to enable flexible operation of a power plant.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention calculates a variable H/N2 from the total head H and rotational speed N of the pump-turbine, and calculates the variable H/N2 from the total head H and rotational speed N of the pump-turbine. When the above-mentioned variable H/N2 is above the upper limit of the operation range of the pump-turbine, a pre-swing is generated in the same direction as the runner's rotation direction, and when the variable H/N2 is below the lower limit of the above-mentioned operation range, it is generated in the same direction as the runner's rotation direction. It is designed to generate a pre-turn in the opposite direction.

(Function) When the operating range of the pump-turbine exceeds the upper limit, water flows to the runner blade 2 at an inflow angle β1 smaller than the artificial angle β of the runner blade 21.
1, the pre-swirl generator 6 is activated to generate a pre-swirl in the water flow on the suction side in the same direction as the rotational direction of the runner 3, so that the water flowing into the runner blades 21 follows the runner blades 21. do. In addition, when the operating range of the pump turbine is below the lower limit, water flows in at an inflow angle β2 larger than the inlet angle β of the runner blade 21, so the water flow on the suction side is given a pre-swirl in the direction opposite to the rotational direction of the runner 3. The water is generated and flows along the runner blades 21. Therefore, even if the upper and lower limits of the operating range of the pump turbine are exceeded, the water flow does not separate and flows along the launch vanes 21, so the operating range can be expanded, and this expansion of the operating range allows the pump By expanding the adjustment range of the shaft input of the water turbine, dynamic operation of the power plant becomes possible.

(Example) Hereinafter, an example of the method for controlling the operation of a pump-turbine according to the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows a vertical shaft Francis type pump-turbine that implements the control method according to the present invention. When operating the pump, the water flow is guided into the runner 3 via the suction pipe 1 and the suction pipe elbow 2, and 3, the water passes through guide vanes 4 arranged in the outer circumferential flow path of the runner 3, and is further pumped to an upper pond (not shown) through a spiral casing 5 on the outer circumference. Runner 3 of single stage pipe elbow 2
A known pre-swing generator 6 such as the opening/closing game 1 is attached to the side end, and a generator aJ machine 8 installed in the building is connected to the main shaft 7 of the runner 3. Further, a rotational speed detector 9 is connected to the generator/motor 8, and a rotational speed signal detected by the rotational speed detector is inputted to the arithmetic unit 11 together with a total head signal detected by the total head detector 10. A variable 11 /' N 2 is calculated, and based on this calculation result, a drive signal is output to the pre-turn generating device 6, indicating whether or not a pre-turn has occurred, and the direction and strength of the pre-turn.

When operating the Francis type pump-turbine mentioned above, first, the pre-swirl generator 6 installed in the suction pipe elbow 2 is
111 to start pumping and shift to pump operation at a pumping height commensurate with the water level between the upper and lower ponds. In this case, the opening degree of the guide vane 4 is set so that the efficiency at the pumping height is the best and the amount of pumped water is maximized.

Therefore, the operating range of the pump-turbine is predetermined at the time of its design, and the operating range is indicated by X as shown in FIG. When the calculated result of the variable H/N2 is greater than or equal to the upper and lower values of the operating range 11/N2 to increase at a predetermined ratio as the pre-turn generator 6 increases.
Activate. On the contrary, the variable T1/N2 of the arithmetic unit 11
When the calculation result is less than or equal to the lower limit value of the above operating range x 2, a negative pre-turn is given in the direction opposite to the rotational direction of the runner 3 as shown in Fig. 2, and this pre-turn is the result of the variable H/N2. The pre-swing generator 6 is configured to decrease at a predetermined ratio as the rotation decreases.
Activate.

By controlling the operation of the pre-swirl generator 6 in this way, when the operation range of the pump turbine is greater than the upper limit x 1, the absolute velocity of the water flowing into the runner blades 21 is as shown in FIG. ■Changes from 1 to ■3, and as a result, the runner blade 21 actually
The direction of the relative velocity of the water flowing into the runner changes from W to W3, and the inflow angle also coincides with β3 and the inlet angle β of the launch blade 21, so water flows in along the runner blade 21, unlike the conventional It is possible to prevent separation of water flow that occurs at the runner blade inlet. In addition, when the operating range of the pump-turbine is lower than the lower limit x 2, the pre-swirl generator 6 is activated.
As shown in the figure, the absolute velocity of water changes from ■2 to v4, and the water flows in along the runner blade 21 at a relative velocity w4 and an inflow angle β4, so it is possible to similarly prevent separation of the water flow at the runner blade inlet. can. This makes it possible to maintain the performance of the pump-turbine even if it exceeds the predetermined operating range X.
By expanding the range of operation 1p7i to
J-like operations can be implemented.

(Effects of the Invention) As is clear from the above explanation, the present invention calculates the variable H/N from the total head H and rotational speed N of the pump-turbine, and calculates the variable H/N from the pump-turbine's total head H and rotational speed N. When the upper limit of the operating range of the water turbine is exceeded, a pre-swing is generated in the same direction as the runner rotation direction, and when the above variable +l/N2 is below the lower limit of the above operating range, a pre-swivel is generated in the same direction as the runner rotation direction. Since pre-swirling is generated, the performance of the pump-turbine can be maintained even beyond the operating range of the pump-turbine determined at the design stage, and the operating range of the pump-turbine can be expanded. By expanding the range, it is possible to expand the adjustment range of the shaft input of the pump-turbine during pumping operation, and it is possible to implement RIIIJl-like operation of the power plant.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a shaft Francis type pump-turbine that implements the pump-turbine operation control method according to the present invention, and Fig. 2 shows the operating range of the pump-turbine that generates pre-swirling according to the present invention. Figures 3 and 4 are velocity triangle diagrams at the runner blade inlet when the operating range of the pump-turbine is exceeded, Figure 5 is a velocity triangle diagram at the conventional runner blade inlet, and Figure 6 is a constant rotation speed. FIG. 3 is a characteristic diagram of a pump-turbine when 2... Suction pipe elbow, 3... Runner, 4... Guide vane, 6... Pre-swivel generator, 8... Power generation type! v1 machine, 9... Rotation speed detector, 10... Total lift detector, 11... Arithmetic device, 21... Runner blade,
X... Operating range of the design M stage, X'... Expanded operating range. Applicant's agent Mr. Sato-IIT Figure 1 Figure 2 Figure 6

Claims (1)

[Claims] In a method for controlling the operation of a pump-turbine in which a pre-swirl generator is provided in the inlet pipe of a pump-turbine in a pump-storage power plant, and the pre-swirl generator is activated during pump operation, the total head H and rotational speed of the pump-turbine are determined. The variable H/N^2 is calculated from N, and when this variable H/N^2 is greater than the predetermined upper limit of the operating range of the pump-turbine, a pre-swing is generated in the same direction as the rotational direction of the runner, and the above A method for controlling the operation of a pump-turbine, characterized in that when the variable H/N^2 is less than the lower limit of the operation range, a pre-swing is generated in the direction opposite to the rotational direction of the runner.