JPS62152399A - Operation of variable speed hydraulic turbine generator - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cavitation at a runner inlet by operating a variable speed hydraulic turbine generator so as to provide a predetermined revolving speed per unit head. CONSTITUTION:A generator 1 is driven by a hydraulic turbine 2. A hydraulic turbine control unit 4 controls the generator 1, instructing to a speed control unit 3 an optimum operating speed n which is determined fused on the model hydraulic turbine characteristic beforehand from the output signal of a speed detector 5 and a head computing element 6. thus, the generator can be controlled stably in an optimum operating condition at all times.

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a method of operating a variable speed water turbine generator, and in particular detects the head of a water turbine and uses this as an input to generate a variable speed turbine generator based on predetermined water turbine characteristics. The present invention relates to a method of operating a variable speed water turbine generator that controls a variable speed water turbine generator.

(B) Prior Art A conventional water turbine without a guide vane or runner vane adjustment mechanism has the characteristics shown in FIG. In Fig. 4, the horizontal axis is the number of rotations per unit head n1, and n
□=n/H. Note that n is the number of revolutions, H is the head, and the vertical axis shows the efficiency.

As can be seen from FIG. 4, the head that gives the highest efficiency is uniquely determined for a certain number of rotations n, and the efficiency decreases even if the head is higher or lower than this. If this head is significantly different from the head that gives the highest efficiency, cavitation will occur at the runner vane inlet, making it impossible to operate. Therefore, conventional constant-speed operation has the disadvantage that efficiency deteriorates due to changes in head, and cavitation occurs at extremely high or low heads, making operation impossible. - Conventional guide vanes or runner vanes to adjust the amount of water A water turbine equipped with this has the characteristics shown in FIG. 5 as an example. The horizontal axis is the rotation speed per unit head mentioned above n1. The vertical axis is the flow rate Q1 per unit head, and Q=Q/H.

As can be seen from Fig. 5, in this water turbine, the number of rotations per unit head is n1 for a certain flow rate per unit head Q1.
The efficiency reaches its maximum value. Connecting the points showing this highest value, we get
It becomes like the line segment AB in FIG. If you drive at a point away from this line segment AB.

Similar to FIG. 4, cavitation occurs at the runner vane inlet, making it impossible to operate, and surging occurs in the partial load region, making operation difficult.

Furthermore, a conventional water turbine equipped with adjustable runner vanes and guide vanes has characteristics as shown in FIG. 6, as an example. In the sixth line segment AB, the line segment AB connects the points showing the highest efficiency, similar to the water turbine having the characteristics as shown in FIG.

Similarly, cavitation occurs at extremely high or low heads, making it impossible to operate.

(c) Problems beyond the problems to be solved by the invention are not limited to fixed specific speed operation water turbines, but also variable speed turbine generators. Operating points (ni,
This problem cannot be solved unless Ql) is calculated and controlled.

(iv) Purpose of the Invention This invention provides information on the head applied to a water turbine, the rotational speed, and, for water turbines with guide vanes and runner vanes, the opening degree of the guide vane and the opening degree of the runner vane. By calculating and controlling the highest operating state of the actual machine conversion characteristics, each operating state (H,
Q) A method of operating a variable speed water turbine generator that enables operation with high efficiency in the case of runner vane inlet, and enables operation even in high head or low head conditions, which conventionally could not be operated due to cavitation occurring at the runner vane inlet. The purpose is to provide

(E) Main Points of the Invention In order to achieve the above object, the operating method of the present invention detects a head and sets a predetermined number of revolutions per unit head.
1, the rotational speed n of the water turbine is calculated backward using the head H detected from the relational expression n = n / H, and the variable speed turbine generator is operated to achieve this rotational speed n, so the runner Prevents cavitation at the inlet. Note that the number of revolutions per unit head with the highest efficiency is uniquely determined from the characteristics of the model water turbine.

Further, according to the present invention, the water turbine is controlled to operate according to the line segment AB shown in FIG. 5 while detecting the head, output, and number of rotations of the guide vane opening (or runner vane opening). Able to drive at its best. In other words, the best stable operating condition can be obtained even at a head where efficiency is extremely poor or operation is difficult due to cavitation at the runner vane inlet.

(F) Embodiment FIG. 1 is a diagram schematically showing a system for explaining the operating method of the embodiment of the present invention, in which a generator 1 is driven by a water turbine 2, and a water turbine control device 4 is used for speed detection. Vessel 5. The generator I is controlled by instructing the speed control device 3 to use the output signal of the head computing device 6 to instruct the optimum operating speed n, which has been determined in advance from the characteristics of the model water turbine. Now, the head HA applied to the water turbine that was operating at point A in Figure 4 has risen to a head H11, and the operating point is
If it drops to ntl=n/Ha, efficiency will drop and cavitation will occur. In the system of this embodiment, the head calculation unit 6 detects that the head changes from HA to H8, and sets the predetermined operating point n, (=n
/Ha), the rotational speed of the water turbine generator is increased, and the water turbine generator is controlled to always operate in the optimum operating range ntA.

FIG. 2 is a diagram for explaining the operating method of another embodiment of the present invention in which the water turbine is equipped with a guide vane or runner vane flow rate adjustment mechanism, where ■ is a generator, 2 is a water turbine, and 3 is a speed control 4 is a water turbine control device, 5 is a speed detector, and 6 is a head calculation unit.Since these configurations are the same as in the first embodiment, their explanations will be omitted, but in this embodiment, the water turbine control device 4 is a speed detector 5, a head calculator 6, a guide vane or runner vane opening detector 7, and a generator output detector 8.
In response to the output signal and the output adjustment command from the system, the guide vane or runner vane opening control command is always placed in advance of the speed control command to control the water turbine generator to the optimum operating state. That is, on the line segment AB in FIG. 5, the guide vane (
(or runner vane) opening degree, flow rate Q per unit head, and efficiency have a one-to-one correspondence, respectively. Therefore, when the head is detected by the head calculator 6, the flow rate Q is determined. There is a one-to-one correspondence between the guide vane (or runner vane) opening and the water turbine output, and a one-to-one correspondence between the turbine output and the generator efficiency, so the generator output ultimately depends on the guide vane (or runner vane) opening. It is a function only of degree and head.

Therefore, by detecting the head, the opening degree of the guide vane or runner vane can be controlled based on the output adjustment command from the system.

On the other hand, regarding the number of rotations per unit head n□.

This also has a one-to-one correspondence with the guide vane (or runner vane) opening on line segment AB, so once this is determined, the rotation speed n can be determined from the detected head.

The above process suffices, and the water turbine generator can be operated in the optimal state while detecting the head by programming the line segment AB representing the optimal operating state determined in advance in the water turbine control device 4. Suppose you are now driving at point 0 in Figure 5. At this time, when receiving a command to increase the output, the water turbine control device 4 detects the head at that time, controls the opening of the guide vane (or runner vane) to a predetermined degree corresponding to the set electric power, and moves to point D. Thereafter, the rotation speed n is calculated so that the corresponding rotation speed n1 is obtained, the rotation speed of the generator is controlled after a delay, and the generator moves to point E to obtain a predetermined output.

Further, if the head HC becomes high at point 0 and reaches Hp and moves to point F, then the guide vane (or runner vane) opening degree at that time is calculated from the set electric power and controlled to point G. Thereafter, the rotation speed is controlled and the process returns to point H.

FIG. 3 is a diagram for explaining the operating method of still another embodiment of the present invention, in which 1 is a generator, 2 is a water turbine, 3 is a speed control device, 4 is a water turbine control device, and 5 is a speed detector. , 6 is a head calculation unit, 7 is a guide vane opening degree detector, and 8 is a generator output detector. These configurations are the same as in the previous embodiment, so their explanation will be omitted, but in this embodiment, the guide In order to adjust both the vane and the runner vane, a runner vane opening detector 9 is provided, and the water turbine control device 4 includes a speed detector 5, a head calculator 6. In response to the output signals of the guide vane opening detector 7, generator output detector 8, and runner vane opening detector 9, and the output adjustment command from the system, the guide vane opening control command is always used to control the runner vane opening and The water turbine generator is controlled to the optimum operating state in advance of the speed control command. That is, for this control.

On line segment AB in Fig. 6, it is given in advance from the model water turbine characteristics as a function of the guide vane opening.

Add this relationship to the program of control bag W4.

This operating method is almost the same as in the above embodiment, and when the head is detected, the guide vane opening degree corresponding to the output command is calculated and the guide vane opening degree is first controlled.

When the guide vane moves, it is detected and the corresponding runner vane opening degree is also calculated.

The rotation speed n is also determined by the same process as in the above example,
The runner vane opening degree and rotation speed n are always controlled behind the guide vane control.

(G) Effects of the Invention As is clear from the above explanation, (1) according to the present invention, the head is detected by the head calculation unit, and the calculation is performed to the optimum operating state determined in advance from the model water turbine characteristics and programmed into the control device. As a result, the guide vane opening is controlled first, and then the rotation speed and runner vane opening (or only the rotation speed if there is no guide vane), so the optimum operating condition is always maintained. It also has the advantage of being able to operate under optimal operating conditions, even in head conditions where efficiency is significantly reduced or cavitation occurs, making operation difficult.

[Brief explanation of drawings]

Fig. 1 is a diagram schematically showing a system for explaining an operating method according to an embodiment of the present invention, and Fig. 2 is a diagram schematically showing a system for explaining an operating method according to another embodiment of the present invention. FIG. 3 is a diagram schematically showing a system for explaining an operating method according to another embodiment of the present invention, and FIG. FIG. 5 is a characteristic diagram of a water turbine equipped with a conventional guide vane or runner vane adjustment mechanism, and FIG. 6 is a characteristic diagram of a conventional water turbine in which both guide vanes and runner vanes can be adjusted. ■... Generator, 2... Water turbine, 3... Speed control device, 4... Water turbine control device, 5... Speed detector, 6...
・Head calculation unit, 7... Guide vane opening degree detector,
- Output detector, 9...Runner vane opening detector. Figure 1 Figure 2 Figure 3 '+ 44fL'J* 'f Ris rotation & Figure 5

Claims (1)

[Claims] 1) A method for operating a variable speed water turbine generator comprising a generator and a high specific speed water turbine or a low specific speed water turbine that drives the generator, in which the head and rotation speed of the water turbine are detected. A variable speed water turbine power generation device that uses this head and rotation speed as input to control the rotation speed of the water turbine generator in an optimum operation range or a safe operation range in accordance with the converted characteristics of the actual machine obtained in advance from the model water turbine characteristics. How to operate the machine. 2) A generator, a water turbine that drives the generator, a speed control device that controls the rotation speed of the water turbine generator, and a guide vane or runner vane that adjusts the amount of water supplied to the water turbine, and In a method of operating a variable speed water turbine generator in which variable speed operation is performed by controlling a control device and a guide vane or runner vane opening, the head and rotation speed applied to the water turbine and the guide vane or runner vane opening are detected. With these rotational speeds or opening degrees as input, the corresponding rotational speed, guide vane opening degree, or runner vane opening degree is determined for a given operation command from the actual operating characteristics obtained in advance from the model water turbine characteristics. The guide vane opening degree or runner vane opening degree is optimized by always prioritizing the guide vane opening degree or the runner vane opening degree over the speed change control of the speed control device so as to achieve the calculated rotation speed and opening degree. A method of operating a variable speed water turbine generator characterized by operating in an operating region or a stable operating region. 3) A generator, a water turbine that drives the generator, a speed control device that controls the rotation speed of the water turbine generator, and guide vanes and runner vanes that adjust the amount of water supplied to the water turbine, and In a method of operating a variable speed water turbine generator that performs variable speed operation by controlling a control device, a guide vane, and a runner vane opening, detecting the head and rotation speed of the water turbine, and the opening of the guide vane and runner vane. Then, using these rotational speeds or opening degrees as input, the corresponding rotational speed, guide vane opening degree, and runner vane opening degree are determined in response to an operation command given from the actual operating characteristics obtained in advance from the model water turbine characteristics. The guide vane opening is always given priority over the speed control device speed change control and the runner vane opening control so that the calculated rotation speed and opening are achieved, and the guide vane opening is adjusted to the optimum operating range. Alternatively, a method of operating a variable speed water turbine generator characterized by operating in a stable operation region.