JPS629747B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a pump-turbine, particularly a high-head pump-turbine in which S-shaped characteristics are inevitable in the operating region of the turbine.

[Background of the invention]

Generally, the runner of a pump-turbine, particularly a high-head pump-turbine, is designed to exhibit sufficient centrifugal pumping action in order to obtain a high head during pump operation.

However, this design adversely affects the turbine operation of the pump turbine. The characteristics of a pump-turbine to which this design is adopted are the number of revolutions per unit head N ₁ and the flow rate per unit head Q ₁ under a predetermined guide vane opening.
When shown by _a characteristic curve representing _{the relationship} between and a second portion in which the value of Q ₁ decreases as the value of Q 1 decreases.

For convenience of explanation, in this specification, the second
This part is called the S-characteristic part. Further, the characteristics of the pump-turbine in the S-characteristic portion are hereinafter referred to as S-characteristics.

The reason for this S-shaped characteristic is that when a water turbine is operating, water normally flows from the outer circumference of the runner toward the center, but as the runner rotates, the centrifugal force acting on the water increases, causing the water to flow. This is thought to be due to the flow being reversed and switching to the pump flow.

Furthermore, it is thought that this is because the flow mode within the runner changes in a complicated manner when approaching this state. Regarding water turbine operation in the S-shaped characteristic section,
The torque per unit head T ₁ also decreases as the rotation speed per unit head N ₁ decreases.

Normally, the operation of the pump-turbine is carried out in the first part. However, due to load breakage or load reduction, the number of revolutions per unit head
If N ₁ increases rapidly, the pump turbine
It will be operated in the character characteristic part. When operation in the S-shaped characteristic section is started, the operating point of the pump-turbine traces the S-shaped characteristic section from one end to the other, and first the flow rate per unit head Q ₁ and the rotation speed per unit head N ₁ are Decrease. After that, Q ₁ and N ₁ will increase as the S-shaped characteristic portion moves in the opposite direction, like a pendulum swinging back. This reciprocating motion in the S-shaped characteristic portion continues almost permanently as long as the guide vane opening remains above a predetermined value, and will not end unless special measures are taken. During this period, the torque T ₁ per unit head also repeatedly decreases and increases.

It is desirable to operate the pump-turbine while avoiding the S-shaped characteristic portion. This is because operation in the S-shaped characteristic part causes abnormal water pressure fluctuations in the penstock and draft tube, including a large water pressure rise and a large water pressure drop, as well as in the pump turbine itself, resulting in intense water pressure. This is because it leads to hammering and sometimes water column separation. The above-mentioned load disconnection is, for example, a method of disconnecting the load disconnector installed between the generator connected to the pump-turbine and the main transformer, thereby preventing the supply of power from the generator to the power grid. Occurs when you stop. It should also be noted that the waiter's hammer is particularly powerful if the penstock and/or draft tubes are long.

The characteristics of a pump water turbine having S-shaped characteristics in the water turbine operation region are shown in FIGS. 1A and 1B.
In FIG. 1A, the characteristics of the pump-turbine are shown as the relationship between the number of rotations per unit head N ₁ and the flow rate per unit head Q ₁ using the guide vane opening as a parameter. On the other hand, in Fig. 1B, the characteristics of the pump-turbine are determined by the same parameters as the number of rotations per unit head N ₁ and the torque per unit head T ₁
It is shown as a relationship with N ₁ , Q ₁ and T ₁
is expressed by the following formula.

N ₁ = N/√, Q ₁ = Q/√, T ₁ = T/H In the above equation, the symbols N, Q, H, and T indicate the rotation speed, flow rate, effective head, and torque of the pump-turbine, respectively. .

Characteristic curves 1 and 1' are obtained under certain relatively large guide vane openings. Characteristic curves 2 and 2' are obtained under smaller guide vane openings. Characteristic curves 3 and 3' are also obtained at smaller guide vane openings.

In the a-d-h portion of characteristic curve 1, Q ₁
The value of decreases as _N1 decreases. As mentioned above, this curved portion a-d-h is referred to as an S-shaped characteristic portion in this specification. Similarly, curve portion bei is an S-shaped characteristic portion of characteristic curve 2, and curve portion cfj is an S-shaped characteristic portion of characteristic curve 3. As is clear at first glance, the S-shaped characteristic portions a-d-h of characteristic curve 1 are similar to the S-shaped characteristic portions a-d-h of characteristic curve 2.
It is longer than the characteristic curve b-e-i, and is
The characteristic curve 3 is longer than the S-shaped characteristic section cfj. This means that as the guide vane opening becomes smaller, the length of the S-shaped characteristic portion becomes shorter.

As in FIG. 1A, in FIG. 1B the curved sections a′-d′-h′, b′-e′-i′ and
―
f'-j' are the S-shaped characteristic portions of characteristic curves 1', 2' and 3', respectively.

FIG. 1B is closely related to FIG. 1A. For example, Q ₁ =Q ₁ x, N ₁ =N ₁ x on curve 3 in Figure 1A.
The point x that satisfies the above corresponds to the point x' on the curve 3' in FIG. 1B. The point x' is T ₁ = T ₁ x', N ₁ =
This is a point that satisfies N ₁ x′ (=N ₁ x). Similarly, the first
Points a, b, c, d, e, f, h, i in diagram A
and j are points a', b', and j in Figure 1 B, respectively.
Corresponds to c′, d′, e′, f′, h′, i′ and j′.

Curve Nr is a no-load flow rate curve. curve 1,
Intersection points α, β, and γ between curves 2 and 3 and curve Nr correspond to intersections α', β', and γ' between curves 1', 2', and 3' and straight line T ₁ =0, respectively.

Next, referring to characteristic curves 1 and 1', the operation of the pump turbine (power generation operation) will be explained. As described above, the characteristics corresponding to characteristic curves 1 and 1' are obtained when the guide vane opening is set to a relatively large value. Normally, the operation of a pump-turbine is as follows:
The upper part of the characteristic curve 1, that is, the S-shaped characteristic part a-
This is done in the curved section above dh. However, if, for example, the load applied to the pump-turbine is suddenly lost, the number of revolutions N of the pump-turbine increases rapidly, so that the value of N ₁ also increases rapidly. Thus, the pump turbine begins to operate in the S-characteristic section. During operation in the S-shaped characteristic section, due to the decrease in the rotation speed N of the pump-turbine,
When the value of N ₁ decreases, the value of Q ₁ also decreases.
Assuming a constant value of H, a decrease in the value of Q ₁ means a corresponding decrease in the pump turbine flow rate Q. In reality, the value of H, that is, the difference in head between the pump-turbine inlet connected to the penstock and the pump-turbine outlet connected to the draft tube, is:
It increases at the same time as the flow rate Q decreases. In this way, once the value of N ₁ decreases, the flow rate Q decreases, and a decrease in the flow rate Q results in an increase in the effective head H of the pump-turbine. This increase in effective head H is further increased by N ₁
A decrease in N ₁ further results in a decrease in Q ₁ . In this way, once the operation in the S-shaped characteristic section begins, Q ₁ and N ₁ will move along the S-shaped characteristic section in the direction of decreasing Q ₁ , that is, in the direction from point a to point h. Continuously decreasing. It can be seen that Q ₁ and N ₁ decrease at an accelerated rate and continuously, as in the positive feedback control circuit.

When the operating point of the pump-turbine finishes tracing the S-shaped characteristic part from point a to point h, the above phenomenon is gradually alleviated in the same way as in the negative feedback control circuit, and then reversed, eventually changing the S-shaped characteristic part to Q. ₁ in the increasing direction, that is, from point h to point a.
Tracing the S-shaped characteristic portion in the opposite direction is also performed in the same manner as the arrow positive feedback control circuit.

While the pump turbine is operated in the S-shaped characteristic section,
The above reciprocating motion is repeated almost permanently.
As explained above, such operation is undesirable. This is because it causes abnormal water pressure changes in each waterway system of a hydroelectric power plant, resulting in severe water hammer and sometimes dangerous phenomena such as water column separation.

It should be noted that these adverse effects associated with driving in an S-shaped section are reduced as the length of the S-shaped section is reduced. For example, if the guide vane opening is made smaller, the S-shaped characteristic part b-
If the pump-turbine is operated according to characteristic curve 2 with ei, the negative effects associated with S-characteristics are reduced.

The operation of the pump-turbine in the S-shaped characteristic portion also has an adverse effect on the torque T of the pump-turbine. When the value of N ₁ decreases in the S-shaped characteristic part, Fig. 1B
As shown in , the value of T ₁ decreases. Here again, points a and h on the characteristic curve 1 shown in FIG. 1A are
It should be noted that they correspond respectively to points a' and h' on the characteristic curve 1' shown in FIG. 1B.

Assuming that the effective head H is constant, a decrease in T ₁ means a decrease in the pump turbine torque T.
Furthermore, it is clear that a decrease in the pump-turbine torque T results in a decrease in the pump-turbine rotational speed N. When the pump-turbine rotation speed N decreases, correspondingly
N ₁ will decrease and then T ₁ will decrease further. In reality, during this period, as mentioned above, the effective head H
This accelerating trend will become even stronger as the number of
In this way, the pump-turbine has the characteristic curve 1
While tracing Q ₁ in the decreasing direction, at the same time the characteristic curve 1'
This means that we are tracing from point a' to point h'. The way to trace this is the same as in the case of a positive feedback control circuit. Thereafter, when the direction of tracing the S-shaped characteristic portion is reversed, the characteristic curve 1' traces from point h' to point a'. Obviously, torque variations as described above are disadvantageous.

Generally, when there is a load or break, the guide vanes are normally closed by the action of the speed governor of the pump turbine. The governor always operates the guide vanes in the direction of closing whenever the actual rotation speed is higher than the set rotation speed (usually the synchronous rotation speed of the generator), but in pump turbines with S-shaped characteristics, the speed governor operates depending on the timing. In this case, there is a possibility that the S-shaped characteristic will be promoted.

Even if there is a load or break, the operating state of the pump-turbine does not fall into the S-shaped characteristic region until the number of revolutions per unit head _N1 reaches point a in Figure 1A. Operation in the S-shaped characteristic portion begins after a certain period of time has elapsed since the load was cut off. During a certain period of time from the moment the load breaks to when it enters the S-shaped characteristic part,
It is desirable that the guide vanes close quickly. This is because, due to this rapid closing operation, the characteristics of the pump-turbine shift to a direction that alleviates the adverse effects caused by the S-shaped characteristic portion. For example, by closing the guide vanes (ie, decreasing the guide vane opening), the characteristics of the pump-turbine represented by characteristic curve 1 in FIG. 1A shift to those represented by characteristic curve 2. Due to this transition, characteristic curve 2 becomes
Since it has an S-shaped characteristic portion smaller than characteristic curve 1, the adverse effects that are problematic are alleviated.

Next, it should be noted that rapid closing of the guide vanes should not be performed when the pump turbine is operated following the S-shaped characteristic section in the direction of Q ₁ decrease. This is because Q ₁ and N ₁ decrease due to rapid confinement, and the influence of the S-shaped characteristic appears more strongly. If the rapid confinement is performed while the S-shaped characteristic portion is being followed in the flow rate decreasing direction, the adverse effects of the S-shaped characteristic portion will be extremely severe.

The method shown in FIG. 2 is disclosed in Japanese Patent Publication No. 49-40902. In this method, after a sudden load is interrupted, the guide vanes are first rapidly closed, and then slowly closed in an operating region where the flow rate decreases significantly as the pump turbine rotation speed increases.
And then it closes quickly. This method has the disadvantage that the timing of the last rapid confinement is not clear. If this rapid confinement
If this is done in an operating condition following an S-shaped characteristic section in the direction of _Q1 decrease, the dangerous situation described above will occur.

Furthermore, while the guide vanes are slowly closing on the way, the pump-turbine should be following the S-shaped part alternately in the _Q1 decreasing direction and increasing direction, so at what point should the last rapid closing of the guide vanes occur? The important issue is whether or not to do so, but there are no regulations regarding this.

Furthermore, JP-A-53-35833 discloses that when controlling the guide vanes as shown in Figure 2, the point C is determined at the point when the pressure in the penstock reaches a certain value. However, the pressure inside the penstock fluctuates widely during transient operation when the guide vane opening changes, resulting in a lack of reliability.

As described above, the conventional techniques have a common drawback in that the timing of the guide vane closing operation is not determined in full consideration of the S-shaped characteristic. In order to avoid disadvantageous abnormal water pressure fluctuations, it is necessary to avoid rapid closing of the guide vanes while the pump-turbine operating condition follows the S-shaped characteristic part in the direction of _Q1 decrease. is necessary. Further, while tracing the S-shaped characteristic portion in the direction of increasing _Q1 , the guide vane should not be opened.

The present inventor analyzed the above-mentioned S-shaped characteristic,
A guide vane control method has been found that yields desirable results. The control method will be described below.

In this method, in order to prevent the negative effects of the S-shaped characteristic caused by the load shedding, the guide vanes are rapidly moved by the action of the speed governor to a predetermined angle or for a certain period of time immediately after the load shedding. Close the guide vane, then slow down the closing speed of the guide vane while following the S-shaped characteristic portion in the _Q1 decreasing direction, and close the guide vane rapidly after completing the S-shaped characteristic in the _Q1 decreasing direction. It is. As can be understood from FIGS. 1A and 1B, when the pump-turbine is operated in the S-shaped characteristic section, ∂Q ₁ ＞/∂N ₁ >0 and ∂T ₁ ＞/∂N ₁ The relationship >0 is satisfied.
When the S-shaped characteristic portion follows the Q ₁ decreasing direction, the relationships dN ₁ /dt<0 and dQ ₁ /dt<0 are satisfied. Here t is time. dQ ₁ /dt
When <0, the relationship dP/dt>0 holds true. (P is the pressure of the penstock.) In this way, S
Detection of pump-turbine operation in the characteristic part is as follows:
This can be done using a number of the relationships described above. More specifically, the detection that the operating state of the pump-turbine is following the S-shaped characteristic part in the direction of _Q1 decrease is based on at least one of the following three conditions.
This can be done by detecting that two conditions are satisfied.

(A) dN ₁ /dt<0 and dQ ₁ /dt<0 (B) dN ₁ /dt<0 and dP/dt>0 (C) dT ₁ /dt<0 and dN ₁ /dt<0 Above explanation As is clear from the above, in the guide vane control characteristics as shown in FIG. 2, it is sufficient to control the point C so that it coincides with the point at which the S-shaped characteristic ends in the _Q1 decreasing direction.

This point is the point where dQ ₁ /dN ₁ changes from positive to negative from Figure 1A (i.e. h in characteristic curve 1, i in characteristic curve 2, 3
j), which changes from time to time depending on the actual operating conditions of the pump-turbine, from N, H, Q, and T to N ₁ ,
Since it is difficult to obtain Q ₁ and T ₁ , we investigated whether it is possible to detect the point at which the S-shaped characteristic Q ₁ has substantially finished decreasing.

As a result, the rotational speed of the water turbine increases at the same time as the load is cut off, and then decreases due to the S-shaped characteristic. However, when the rotational speed reaches a certain rotational speed passing point while decreasing, the flow rate decreases due to the S-shaped characteristic. It has been found that the ending point tδe almost coincides with the end point tδe.

[Purpose of the invention]

An object of the present invention is to rapidly close the guide vane when the load is interrupted, then shift to gentle closing, and then quickly close again, which is the so-called three-stage closing of the guide vane. An object of the present invention is to provide a control device for a pump water turbine that can detect timing with good reliability.

That is, an object of the present invention is to detect how the operating point of the pump-turbine follows the S-shaped characteristic portion from the pump-turbine rotation speed N, which can be detected by a highly reliable mechanical switch. The present invention provides a control device for a pump-turbine that is capable of

[Summary of the invention]

The present invention was made based on the discovery that when the operating point of the pump-turbine is in the S-shaped characteristic portion, the operating state of the pump-turbine is clearly reflected in its rotation speed.

In other words, the feature of the present invention is that in the water turbine operation range, the number of rotations per unit head of the pump water turbine is
If N ₁ , flow rate per unit head Q ₁ and generated torque per unit head T ₁ , then N ₁ = N/√, Q ₁ = Q/√, T ₁ = T/H (however, N, Q, T and H indicate _the rotation speed, flow rate, torque _, and effective head of _the pump-turbine. A characteristic curve diagram of a water turbine, showing the rotation speed N ₁ , flow rate Q ₁ , and generated torque.
It has an S-shaped characteristic in which T ₁ decreases at the same time, and when the load suddenly decreases or breaks, the guide vanes are closed quickly to the specified opening and the operating state of the water turbine changes in the direction of flow reduction on the S-shaped characteristic. Alternatively, the guide vanes may be closed gently while the torque is decreasing, and then when the operating state of the water turbine begins to follow the S-shaped characteristic in the direction of increasing flow rate, the guide vanes may be rapidly closed based on the governor's command. In the configured pump-turbine control device,
A device that memorizes that the rotation speed has increased from the rated rotation speed N ₀ to a predetermined rotation speed N ₁₀ , and a device that records that the rotation speed that has increased thereafter falls below the predetermined rotation speed N ₁₀ and is higher than the rated rotation speed N ₀ . A device is provided to detect when the rotational speed has become lower than a second predetermined rotational speed N ₂₀ , and the second predetermined rotational speed N ₂₀ is determined at a time when the rotational descent curve is about to shift from an upward convexity to a downward convexity. Under the condition that the detection device is activated after the storage device is selected to approximately match the rotational speed, the operating state of the water turbine will begin to follow the S-shaped characteristic from the direction of decreasing flow rate to the direction of increasing flow rate. A control device for a pump-turbine equipped with a means for detecting whether a point is being reached when the

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG. FIG. 3 shows the guide vane opening degree A, the pump-turbine rotation speed B, and the water pressure C on the upstream side of the pump-turbine (iron pipe) after the load failure occurs at time _t0 . In this figure, N ₁ and Q ₁ are calculated from the water turbine rotation speed N and the difference H between the water pressure on the upstream side of the pump-turbine and the water pressure on the downstream side.
The part corresponding to is indicated by _δB .

From the observation in Figure 3, the reason why the operating point of the pump-turbine follows the S-shaped characteristic part δ _B in the direction of decreasing flow rate is because the rotation speed N is decreasing and the rotation speed N is lower than the rated rotation speed N ₀ . It can be seen that this is a fairly high range.

The rotation speed B in Fig. 3 is when the guide vane opening is close to fully open, and the dotted line B' is when the guide vane opening is medium (corresponding to characteristic 2 in Fig. 1 A). In both cases, the rotational speed N is around _N20 and coincides with the end point tδe of _δB . Furthermore, this point of substantially matching is close to the point where each rotational speed variation curve changes from upwardly convex to downwardly convex.

This can be determined in advance from the characteristic curve of the pump-turbine to the water-turbine rotation speed N ₂₀ at the end point tδe of δ _B.
This shows that it is configurable.

On the other hand, since the water turbine rotational speed passes through the _N20 point in the process of increasing at the same time as the load is cut off, it is necessary to find the _N20 point while the rotational speed is falling, not the N20 point in the process of increasing the _rotational speed.

Therefore, in the present invention, the rotation speed is slightly higher than N ₂₀ .
A first rotation speed switch that operates at N ₁₀ , means for storing that the first rotation speed switch is activated, and a second switch that operates at N ₂₀ or less are provided, and the storage means and the second rotation speed switch are provided. When the switch is activated, the end point tδe of _δB is detected and the guide vane is suddenly closed.

4 and 5 show a pump-turbine control device implementing the present invention. FIG. 4 shows the guide vane servo motor. In the normal state, the solenoid 6a is energized, the valve 6 is in the state shown, and the pressure oil PO ₁ is supplied to the stopper piston 1.
1 to move the piston 11 into the cylinder 1.
0, and the lever 8 is displaced downward. Control of the guide vane servo motor 21 is entrusted to control of the control oil pressure 24 applied to the lower chamber of the relay servo motor piston 18 that drives the main pressure distribution valve plunger 13 . The control oil pressure 24 is given by a speed governor, and increases or decreases depending on the deviation between the commanded opening degree of the guide vane servo motor and the actual opening degree, which is determined according to the deviation between the control target rotational speed and the actual rotational speed.

Now, the load has broken and the rotation speed has changed to the rated rotation speed.
When rising above N ₀ , the governor control communicates the control hydraulic pressure 24 to the discharge side. Then, the relay servo piston 18 is pushed down by the pressure oil PO ₂ . That is, the main pressure distribution valve plunger 13
is the preset stop nut 16-
1, descend to the position limited by 16-2. Thus, the pressure oil PO ₃ operates the guide vane servo motor pin 22 in the closing direction via the line 20. When the guide vane opening degree is closed to the opening degree Ya corresponding to point B in FIG. 3, the control circuit for the solenoid 6a shown in FIG. 5 is activated.

The solenoid 6a is a normally closed contact of the relay 25, 2
5b and the normally open contact 26a of the relay 26,
It is inserted between the control power supply P ₁ and N ₁ .

32 is a low power switch that detects generator load loss and closes; 29 is a switch that closes when the guide vane opening Y becomes less than the set opening Ya shown in Fig. 3; When the opening becomes less than Ya, both switches 32 and 29 are closed and the relay 25 is energized, so the b contact of the relay 25 opens and the solenoid 6a is deenergized (at this point, Contact 26a is open.).

When the solenoid 6a is deenergized, the valve 6 shown in FIG. 4 is switched, and the pressure oil PO ₁ acts below the stopper piston 11 to pull the piston 11 upward. Then, the lever 8 rotates around the fulcrum 7, lifts up the stopper plate 9, and pulls up the plunger 13 of the main pressure regulating valve 14 and the relay servo motor piston 18 via the rod 12.

When the plunger 13 is pulled upward, it is in a position to supply a small amount of pressure oil PO ₃ to the pipe line 20. In other words, the hydraulic pressure 24 based on the governor command
Irrespective of this, PO ₃ is introduced into the left chamber of the piston 22 through the conduit 20 with the throttle applied, and the piston 22 is slowly driven in the closing direction. The closing speed of the guide vane at this time has the characteristic between the loaf and the loaf shown in FIG.

On the other hand, the rotation speed N of the pump-turbine increases due to load interruption, and N>N ₁₀ (N ₁₀ is the specified rotation speed).
Then, contact 31 (the contact that turns on when N>N ₁₀ ) turns on. Then, the normally open contact 27a, which also forms a self-holding circuit, closes, and the relay 27 continues to be ON even if N becomes less than _N10 . In other words, the relay 27 remembers that the rotational speed N has once risen above _N10 .

Eventually, the number of revolutions of the pump-turbine drops and the second
Contact ₃₀ (N<
The contact that turns on when _N20 is turned on, and the relay 26 is turned on via the normally open contact 27a of the relay 27, which has been turned on in advance.

Then, the normally open contact 26a in series with the solenoid 6a, which has been OFF until now, turns ON, so the solenoid 6a returns to the ON state again.

That is, the solenoid is deenergized only from _t1 to _t2 , which corresponds to B to C in FIG. In other words, from t ₁ to t ₂ , the predetermined slow closing speed is maintained regardless of the actual rotation speed.

When the solenoid 6a is energized, the valve 6
In the state shown in the figure, the guide vanes are controlled by the speed governor. In the characteristics shown in FIG. 3, the actual rotational speed is higher than N ₀ even at point t ₂ , so the servo motor is driven in the direction to close the guide vane.

In the control circuit shown in FIG. 5, when the load is restored, the low power switch 32 is opened and all relays and contacts are reset.

〔Effect of the invention〕

As is clear from the above, the present invention detects the delicate timing when following the S-shaped characteristic by simply combining a mechanical speed switch, and the detection can be performed easily and with high reliability. You can control the storm.

[Brief explanation of the drawing]

Fig. 1A and Fig. 1B are explanatory diagrams of S-shaped characteristics peculiar to pump-turbine, Fig. 2 is a guide vane control characteristic diagram of the conventionally known quick-slow-fast three-stage closing system, and Fig. 3 is
FIG. 4 is a diagram of a transient response when the pump-turbine load sheath is cut off to which the present invention is applied, FIG. 4 is a schematic diagram of a device for realizing the present invention, and FIG. 5 is a control circuit diagram of a solenoid. N...rotational speed, H...effective head, Q...turbine flow rate, T...turbine torque, _H1 ...rotational speed per unit head, _Q1 ...turbine flow rate per unit head,
T ₁ ... Water turbine torque per unit head, 6 ... Valve, 6a ... Solenoid, 11 ... Stopper piston, 14 ... Main pressure distribution valve, 16-1, 16-
2,17-1,17-2...Stopnut, 2
2... Guide vane servo motor piston, 30...
Second speed switch, 31...First speed switch, 32...Low power relay.

Claims (1)

[Claims] 1 In the water turbine operation range, if the number of rotations per unit head of the pump turbine is N ₁ , the flow rate per unit head Q ₁ , and the generated torque per unit head T ₁ , then N ₁ = N/√ , Q ₁ = Q/√, T ₁ = T/H (N, Q, T, and H indicate the rotation speed, flow rate, torque, and effective head of the pump-turbine), and the rotation of the horizontal axis Number N ₁ and flow rate on vertical axis
This is a characteristic curve diagram of a pump-turbine showing the relationship between Q ₁ and generated torque T _1. It has an S-shaped characteristic in which rotation speed N ₁ , flow rate Q ₁ , and generated torque T ₁ all decrease, and when the load suddenly decreases or the load increases. Due to a breakage, etc., the guide vanes are rapidly closed to the specified opening degree, and the operating state of the pump-turbine becomes S.
While the flow rate is decreasing or the torque is decreasing on the S-shaped characteristic, the guide vanes are closed gently, and when the pump-turbine operation status starts to increase in the flow rate on the S-shaped characteristic, the governor command is A device for storing when the rotation speed has increased from the rated rotation speed _N0 to a predetermined rotation speed _N10 in a control device for a pump water turbine configured to rapidly close the guide vanes based on the invention;
comprising a device for detecting that the rotational speed that has subsequently increased has fallen below the predetermined rotational speed N ₁₀ and has become lower than a second predetermined rotational speed N ₂₀ which is higher than the rated rotational speed N ₀ ; The second predetermined rotational speed N ₂₀ is selected so as to substantially match the rotational speed at which the rotational speed decreasing curve is about to shift from an upward convexity to a downward convexity. After the storage device is activated, the detection device is activated. A control device for a pump-turbine, comprising means for detecting a point in time when the operating state of the water turbine starts to follow an S-shaped characteristic from a direction of decreasing flow rate to a direction of increasing flow rate.