JP2695838B2 - How to control hydropower equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an output control method during a power generation operation of a hydroelectric power plant.

(Prior Art) In a hydraulic power plant equipped with a hydraulic machine such as a turbine or a pump turbine, the shaft output during the operation of the turbine is determined only by the opening degree of the guide vanes under a condition of a constant head. When the output of the electric motor is changed, it is customary to control the opening and closing of the guide blades so that the blade opening degree corresponds to the output target value.

Fig. 7 shows the schematic configuration of the hydroelectric power plant.
The water flows into the water turbine 3 through the penstock 2, drives a generator 4 directly connected to the water turbine 3, generates power, and is discharged to a lower pond 6 through a water discharge channel 5.

A method of controlling the output of the generator in the hydroelectric power plant having such a configuration will be described with reference to FIG. 8. The flow rate of the water turbine flowing into the runner 7 of the water turbine 3 driving the generator 4 is around the runner. It is adjusted by changing the opening degree of the arranged guide vanes 8. The opening of the guide blade is adjusted by an opening adjuster 9. The opening adjuster 9 outputs a target opening signal a * according to a difference ΔP ^* between the output target value P ^* and the actual generator output Pg, and adjusts the opening of the guide blade 8.

FIG. 9 shows an example of output control when the output is changed in this way. In this figure, the horizontal axis indicates time T, and the vertical axis indicates generator output P, guide vane opening a, flow rate Q of the turbine, and effective head He of the turbine. , Generator output P, the solid line indicates the actual generator output Pg, and the dashed line indicates the output target value P ^* .

As is clear from this figure, the actual generator output Pg is
Immediately after the point A at which the output starts to change, a phenomenon is shown in which the output is once increased and then decreased, although the output is largely deviated from the output target value P ^* and the output is reduced. This phenomenon is caused by water hammer in a penstock connected to a water turbine.

That is, in the case of changing the flow rate Q of the water turbine by changing the opening degree of the guide blade in the hydroelectric power generation equipment of FIG.
The water pressure H1 at the inlet of the water turbine 3 and the water pressure H2 at the outlet thereof change as follows due to the water hammer action of the penstock 2 and the water discharge channel 5.

H1 = − (L1 / gA1) (dQ / dt) + H10 (1) H2 = (L2 / gA2) (dQ / dt) + H20 (2) where L1: Pipe length of penstock 2 L2: Pipe length of water discharge channel 5 A1: Cross-sectional area of penstock 2 A2: Cross-sectional area of water discharge channel 5 g: Acceleration of gravity H10: Water pressure at inlet before flow change H20: Water pressure at outlet before flow change Here However, to simplify the problem, assuming that the loss in the pipeline is zero and the dynamic pressure is negligible, the effective head of the turbine
He is He = H1−H2 (3), and the water level difference Hst between the upper and lower ponds is Hst = H10−H20 (4). Therefore, He is obtained from the above equations (1) and (2). =-{(L1 / gA1) + (L2 / gA2)} x (dQ / dn) + (H10-H20) =-{(L1 / gA1) + (L2 / gA2)} x (dQ / dt) + Hst ... ... (5)

From this equation (5), when the opening of the guide vanes is reduced to reduce the generator output Pg, the flow rate Q of the turbine decreases, and (dQ / d
When t) becomes negative, the effective head He of the turbine becomes the value Hst before the change.
You can see that it increases more.

Since the output of the turbine is proportional to the product of the flow rate Q and the effective head He, if the effective head He increases beyond the decrease rate even if the flow rate Q of the turbine decreases, the actual generator output Pg increases. As a result, the decrease shown in FIG. 9 occurs.

For the same reason, a similar phenomenon occurs when increasing the generator output Pg. That is, when the guide blades are opened, the flow rate Q of the water turbine increases, but the effective head He of the water turbine of the water hammer action shown in equation (5) decreases, so that the output of the water turbine decreases and the generator output P temporarily decreases. To decrease.

(Problems to be Solved by the Invention) As described above, in the conventional method of controlling a hydroelectric power plant, the output of the generator once responds in reverse to the request from the power system. Had become.

The present invention has been made in order to solve the above-mentioned drawbacks in the prior art, and has a control method of a hydroelectric power generation facility that has a good ability to follow an output request from an electric power system and can stably control the output. It is intended to provide.

[Configuration of the invention]

(Means for Solving the Problems) The present invention is directed to a hydroelectric power plant including a hydraulic device such as a water turbine or a pump turbine whose output is controlled by a guide blade, and a generator or a generator motor. When the degree is controlled in accordance with the difference ΔP ^* between the output target value P ^* of the generator or the generator motor and the actual output Pg, the actual head difference between the upper and lower ponds is detected, and A time constant Ta corresponding to the actual head detected based on the relationship between the head and the time constant Ta is determined, and the control is performed via an integration circuit or a delay circuit to which the determined time constant Ta is applied. Is what you do.

In addition, the present invention includes a plurality of hydraulic devices such as a water turbine or a pump turbine whose output is controlled by the guide blades, and a generator or a generator motor, and the plurality of the hydraulic devices share one pipe. When the opening degree of the guide vanes is controlled in accordance with the difference ΔP ^* between the output target value P ^* of the generator or the generator motor and the actual output Pg, the operation of The time constant Ta corresponding to the number of operating hydraulic equipment is determined based on a predetermined relationship that reduces the time constant Ta in response to the increase in the number of hydraulic equipment during operation. The control is performed via an applied integration circuit or delay circuit.

(Operation) Next, the operation of the method for controlling a hydroelectric power plant of the present invention will be described.

As described above, in order to prevent the generator output from once responding in reverse to the request from the power system, the transient increase or decrease of the effective head He of the turbine shown in Expression (5) is suppressed. do it. In this case, if the waterway system is determined, the lengths L1 and L2 of the pipeline and the cross-sectional areas A1 and A2 do not change. Therefore, to suppress the change in the effective head He of the turbine, the time change rate (dQ / d
It suffices to reduce t).

Therefore, in the present invention, in order to slow down the speed of the change of the guide blade that causes the change of the water turbine flow rate Q, the guide blade is controlled slowly through the integration circuit or the delay circuit of the predetermined time constant Ta. .

In this case, the time constant Ta of the integrating circuit or the delay circuit (hereinafter simply referred to as the integrating circuit) and L1, L2, A1, A2, Hs of the equation (5)
The relative ratio with the time constant Tw of the pipeline determined from t and the like needs to be larger than a predetermined value. Where the pipe time constant Tw
Is Tw = (Q0 / gHst) × (L1 / A1 + L2 / A2) (6) where Q0 is the turbine flow rate before the change, and the time constant Tw of the pipeline changes depending on the operating conditions of Q0 and Hst. Therefore, the time constant Ta of the integrating circuit also needs to be changed according to the operating conditions.

Here, the time constant Ta of the integrating circuit with respect to the time constant Tw of the pipeline is
Can be determined based on the concept described below.

That is, when the response of the generator output Pg to the guide blade opening a is represented by a transfer function, Pg = {(1-TwS) / (1 + 0.5TwS)} a (7) where S: Laplace operator and Become.

If the transfer function of the integrating circuit is (1 / TaS), the difference ΔP *
The transfer function of the guide vane opening a becomes _{^{a = ΔP * / T a S}} ...... (8) for. Moreover, the response of the actual generator output Pg with respect to the output target value ^{P *,} expressed by the transfer ^{function, Pg = P * (1-} TwS) / {0.5T a T w S 2 + (T a -T w) S + 1｝ (9) The method of deriving the expression (9) from the expressions (7) and (8) is as follows. That is, since the definition of ΔP ^* is as follows from FIG. 8, ΔP ^* = P ^* −Pg From the above equation and equation (8), Becomes

Eliminating the guide blade opening a from the above equation and equation (7) gives Becomes If this equation is further transformed, Equation (9) can be derived as described above.
When the response of the actual generator output Pg to the change in the output target value P * is calculated from this equation, the result is as shown in FIG. Here, the straight line m0 indicates a change in the output target value P *, and the curves m1 and m
2, m3 is the generator output Pg when the time constant Ta changes
Is shown.

Here, the response of the generator output Pg is as follows according to the relative ratio between the time constant Ta of the integrating circuit and the time constant Tw of the pipeline.

When T _a <T _w , the system becomes unstable.

Then, the generator output Pg is a response that temporarily changes in the reverse direction as shown by the curve m1.

, The generator output Pg shows a response that changes only slightly in the opposite direction, as shown by the curve m2.

In this case, the generator output Pg shows a response like the curve m3 and does not change in the reverse direction, but the followability to the output target value P ^* deteriorates.

To prevent the phenomenon of changes in the direction opposite to the direction to be the actual generator output Pg control As apparent from the above description, constant T _a of the integrating circuit is constant T _w when the pipe for You can see that However, constant T _a of the integrating circuit when is too large, follow-up property is deteriorated with respect to the output target value P ^*.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. In these figures, the same parts as those in FIGS. 7 to 9 are denoted by the same reference numerals.

The first embodiment of the present invention relates to a hydraulic power plant having the same configuration as that of FIG. This is realized by: Where the time constant of the pipeline
Tw is expressed by the equation (6) in the waterway system shown in FIG. In this case, Q0 has the maximum flow rate in practical use, and its change due to the operation state can be ignored.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the opening adjuster 9 'is provided with the above-mentioned integral time constant.
It does not have Ta, and instead, before the opening adjuster 9 ',
A first-order lag circuit whose time constant corresponds to the above Ta, for example, a filter circuit 10, is inserted. After the difference ΔP ^* is converted into a slow signal ΔP ^** by the filter circuit 10, the opening adjuster 9 'is controlled.

In each of the above embodiments, the time constant Tw of the pipeline changes depending on the water level difference Hst between the upper pond and the lower pond. It is desirable. FIG. 3 shows a specific example of the configuration.
11 and a time constant setting device 12 are added.

In this embodiment, the water level differences H10 and H20 are guided to the water level detector 11 to calculate a head (actual head) Hst, and the head Hst is input to a time constant setting device 12, and a predetermined head Hst and a time constant Ta
The time constant Ta is calculated based on the relationship This time constant Ta
Is input to the filter circuit 10, and the time constant is set to Ta.

Here, the relationship between the head Hst and the time constant Ta may be such that Ta is continuously changed with respect to the change of the head Hst as shown by a solid line in FIG. May be changed stepwise at Hst0 intermediate between Hst min and Hst max as indicated by the dashed line.

By the way, the value of the time constant Tw of the pipeline differs in the branch waterway system in which a single pipeline is shared by a plurality of water turbines, depending on the number of operating turbines. That is, as shown in FIG. 5, for example, two water turbines 3 are connected to one pipe (hydraulic iron pipe) 2 through branch pipes 13a and 13b.
a, 3b, and the drainage pipes 14a, 14b of these turbines are connected to the lower pond 6 through the spillway 5,
The penstock 2 from the upper pond 1 to the junction 15 and the water discharge channel 5 from the junction 16 to the lower pond 6 are commonly used by two water turbines. Pipe time constant Tw
1, Tw2 is as follows. For simplicity, the lengths L2a, L2b, L3a, L3b and cross-sectional areas A2a, A2b, A3a, A3b of the branch conduits 13a, 13b and the discharge pipes 14a, 14b are L2a = L2b = L2 (10) L3a = L3b = L3 (11) A2a = A2b = A2 (12) It is assumed that A3a = A3b = A3 (13).

Single-unit operation: Tw1 = (L1 / A1 + L2 / A2 + L3 / A3 + L4 / A4) x Q0 / gHst ... (14) Twenty-unit operation: Tw2 = (2L1 / Al + L2 / A2 + L3 / A3 + 2L4 / A4) x Q0 / gHst ... … (15) In the above equation, if L2 / A2, L3 / A3 can be ignored for L1 / A1, L4 / A4, then Tw2 = 2Tw1 …… (16) Therefore, the time constant Ta is set accordingly. Just change it.

An embodiment suitable for this is shown in FIG. In this embodiment, a time constant switch 17 according to the number of operating turbines is added to the apparatus shown in FIG. 1. A signal Nd indicating the number of operating water turbines is input to the time constant switch 17, and the time constant Ta of the filter circuit 10 is used. Switch. In this case, the time constant Ta is smaller when operating one turbine than when operating two turbines, so that the response of the generator output Pg to the output target value P * can be made faster.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a control method for a hydroelectric power generation facility that has good responsiveness to an output request from a system and can stably control the output.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is a time constant.
FIG. 3 is a graph showing how the generator output Pg changes when Ta changes. FIG. 3 is a system diagram showing another embodiment of the present invention.
Fig. 3 is a graph showing the operation of the embodiment of Fig. 3, Fig. 5 is an explanatory diagram illustrating a branch waterway system hydroelectric power plant to which the present invention is applied, and Fig. 6 is a system showing another embodiment of the present invention. FIG. 7, FIG. 7 is a schematic diagram showing a schematic configuration of a general hydroelectric power plant, FIG. 8 is a system diagram showing a conventional operation control method, and FIG. 9 is a graph showing an operation in the case of the method of FIG. is there. 1 ... Upper pond, 2 ... Penstock, 3 ... Turbine, 4 ... Generator, 5 ... Drainage channel, 6 ... Lower pond, 7 ... Runner, 8 ...
Guide vanes, 9, 9 '... opening regulator, 10 ... filter circuit, 11 ... water level detector, 12 ... time constant setting device, 17 ... time constant switching device.

Claims (2)

(57) [Claims] 1. A hydraulic power plant comprising a hydraulic machine such as a water turbine or a pump turbine whose output is controlled by a guide blade, and a generator or a generator motor, wherein the opening of the guide blade is controlled by the generator or the generator motor. When the control is performed according to the difference ΔP ^* between the output target value P ^* and the actual output Pg, the actual head difference between the upper pond and the lower pond is detected, and the relationship between the predetermined actual head and the time constant Ta is determined. A method for controlling a hydroelectric power plant, comprising: obtaining a time constant Ta corresponding to an actual head detected based on the calculated time constant Ta; and performing the control via an integrating circuit or a delay circuit to which the obtained time constant Ta is applied. 2. A hydraulic turbine, comprising: a plurality of hydraulic machines such as a water turbine or a pump turbine whose output is controlled by guide vanes; and a generator or a generator motor, wherein the plurality of hydraulic machines share one pipe. Of the branch waterway system
When controlling the opening degree of the guide vanes in accordance with the difference ΔP ^* between the output target value P ^* of the generator or the generator motor and the actual output Pg, in response to an increase in the number of operating hydraulic equipment, Based on a predetermined relationship for reducing the time constant Ta, a time constant Ta corresponding to the number of operating hydraulic equipment is determined, and the determined time constant Ta is applied via an integration circuit or a delay circuit to which the determined time constant Ta is applied. A method for controlling a hydroelectric power plant, comprising performing control.