JPS6132507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water level regulating device for controlling the flow rate of a water turbine based on the water level of a regulating pond in a run-of-river hydroelectric power plant.

Run-of-river hydropower plants have small capacity regulating reservoirs, so they are operated using the same amount of flow as the inflow into the regulating reservoir. In other words, the water level in the regulating pond is detected and the output of the water turbine is automatically controlled so that the water level remains constant. As shown in FIG. 1, in the run-of-river power plant PS2, the flow rate _Q1 normally used in the upstream power plant PS1 flows into the regulating pond 1. Therefore, the output of the hydroelectric power station PS2 is controlled so that the flow rate _Q1 and the flow rate _Q2 flowing through the pressure conduit 2 are equal, that is, the water level _h1 of the regulating pond is constant. As a result, the relationship between Q ₃ flowing through the pressure iron pipe 4 and the flow rates Q ₁ and Q ₂ is controlled so that the following equation (1) holds steadily.

Q ₁ = Q ₂ = Q ₃ ...(1) Here, the surge tank 3 is connected to the downstream power plant PS2.
They are provided to absorb pressure shock waves that occur when a generator's load is cut off, etc., and generally have a small capacity. Steady surge tank 3 water level
h ₂ is a value lower than the water level h ₁ of the regulating reservoir 1 by the head loss of the pressure headrace 2 so that the same flow rate Q ₂ as the inflow Q ₁ to the regulating reservoir 1 flows through the pressure guide channel 2. It is becoming.

FIG. 2 shows an example of a control block diagram representing the operation of a conventional water level adjusting device applied to a waterway system as shown in FIG.

Assuming that the inflow Q ₁ from the upstream power plant PS 1 increases now, the water level h ₁ of the regulating pond rises with the slope of the integral time constant T ₁ of the regulating reservoir 1 . This water level h ₁ is the adder 1
3 is compared with the reference water level _h1R . The reference water level _h1R defines the water level of the regulating pond 1 at the time of the rated output of the water regulating vehicle installed in the power station PS2. Since the reference water level h _1R is a constant value, when the water level h ₁ rises, its deviation Δh (Δh=h ₁ −h _1R ) is no longer zero. This deviation Δh is converted into a signal that takes into account the water level adjustment rate H _R , that is, a flow rate signal, and is input to the adder 14 . Here, water level adjustment rate H _R means water level change △
How much guide vane opening △η (flow rate) for h
This is a coefficient that determines whether the value should be changed.

When a signal corresponding to the water level change Δh is inputted to the adder 14, the guide vane is opened by the amount corresponding to the inclination of the time constant T of the guide vane operation. Note that in order to prevent the guide vane opening degree η ₂ from going too far, the guide vane opening degree signal η ₂ is fed back to the adder 14 . When the guide vane opening degree η ₂ changes, due to the first-order lag characteristic determined by the rated flow rate Q _R of the water control turbine and the water turbine gate time constant T _G , the water turbine flow rate increases by an amount corresponding to the change in the guide vane opening degree η ₂ .
Q ₃ increases. When the water turbine flow rate Q ₃ increases, the surge tank water level h ₂ decreases at a slope of the integral time constant T ₂ due to the difference with the flow rate Q ₂ of the pressure headrace 2. Due to the difference between the surge tank water level _h2 and the regulating pond water level _h1 ,
The flow rate Q ₂ of the pressure conduit 2 increases, and when Q ₂ and Q ₃ become equal, the surge tank water level h ₂ stops decreasing.

The surge tank water level h ₂ is stabilized when the inflow Q ₂ to the surge tank 3 is equal to the turbine flow rate Q ₃ , and the same flow rate as the inflow Q ₁ to the regulation pond 1 is the same as the inflow into the pressure conduit 2 . This is when the water level reaches a point where it can flow. i.e. surge tank water level _h2
This is when the water level becomes lower than the regulating pond water level _h1 by the head loss of the pressure headrace 2.

However, in this case, the water level _h1 of the regulating pond is calculated using the following formula:
Set the water level to a value determined by (2). This is because there is a delay in phenomena such as the time constant T ₁ of the regulating pond 1, the time constant T ₂ of the surge tank 3, and the time constant T _G of the water turbine gate.

△h ₁ = H _R・△Q ₁ /Q _R ...(2) In formula (2), △h ₁ is the change in the water level h ₁ of the regulating pond (m) and H _R is the water level adjustment rate (m/pu) △Q ₁ is the change in the inflow Q ₁ (m ³ /sec) Q _R is the rated flow rate of the water control vehicle (m ³ /sec / pu) Conversely, the inflow Q ₁ to the regulating reservoir 1 has decreased In this case, the flow rate _Q3 of the water control vehicle decreases and the water level of the control pond decreases.
h ₁ is settled at the water level that has fallen by △h ₁ as shown in equation (2).

In addition, when surging occurs between the regulating reservoir 1 and the surge tank 3, the incomplete differentiation circuit 12 prevents the surge tank water level _h2 and the regulating reservoir 1 water level _h1 from divergence due to the surging. (For example, Japanese Patent Publication No. 39-8722).

By the way, in such a waterway system, in order to perform stable water level adjustment operation even if the water level rises or falls and settles, it is necessary to set the second turning point of the round transmission relationship in the block diagram of Fig. 2 as is well known. If the gain of is −3dB or less, the water level adjustment rate H _R is calculated by the formula
It is necessary to take a value larger than the value of (3).

Here, H _R min is the water level regulation rate at the stability limit Q _R is the rated flow rate of the water control vehicle Zox, and Tox is the transfer function h ₁ (S)/Q ₃ (S) including the regulation pond and pressure headrace channel Zox. /1+T
The value T when approximated to oxS is a temporary delay time constant of the water level adjustment device.

Generally, T is 10 seconds and 1<Tox/T, so equation (3)
can be approximated as in equation (4).

H _R min=Q _R・Zox/Tox・T ……(4) If the water surface area of regulating pond 1 is A, then Tox in equation (4)
is almost proportional to A, so if Tox=KA, the formula
(4) becomes H _R min=Q _R・Zox/A・T/K ……(5). Equation (5) shows that if the water surface area A of the regulating pond 1 is smaller than the rated flow rate Q _R of the water control vehicle, stable water control will not be possible unless the stability limit water level regulation rate H _R min is increased. It means you can't drive.

In existing power plants, the rated flow rate Q _R of the water turbine, the water surface area and water depth of the regulating pond 1 are fixed, and in the newly built power plant, the rated flow rate Q _R of the water turbine is determined based on water system operation, and adjustment is required. The water surface area and water depth of Pond 1 are determined by the economic efficiency of civil engineering work or physical size restrictions.
It is designed to have a value that is not too large. When performing water level adjustment operation in such a regulating pond, although it is necessary to increase the water level adjustment rate, the water depth cannot be increased due to physical dimensions, so submerged adjustment operation cannot be performed. There was an inconvenience.

The present invention was made in view of this current situation, and compared to the rated flow rate of the water conditioning vehicle of the downstream power plant, the
To provide a water level adjustment device capable of stably performing water level adjustment operation over the entire range of rated output of a water control vehicle even if the product of water surface area and water depth is small.

In order to achieve this objective, in the present invention, when the flow rate _Q1 flowing into the regulating pond changes, even if the water level in the regulating pond does not actually change, the guide vane opening of the downstream power plant is adjusted in advance before the change. It is characterized by changing η ₂ to eliminate the water level deviation △h ₁ during settling caused by the delay in the waterway system.

An embodiment of the present invention will be described below with reference to the block diagram shown in FIG. Water level adjustment device 1 of the present invention
1 is characterized in that a function generator 17 and an adder are added to the conventional water level adjusting device 11. η ₁ is
This is the guide vane opening signal of the upstream power station PS1, and the other symbols are Q ₁ , Q ₂ , Q ₃ , h ₁ , h ₂ , h _1R ,
η ₂ , Q _R , T _G , T ₁ , T ₂ , 12, 14, 15,
H _R and S (Laplace operator) are the same as in FIG. 2. Further, 18 is a converter.

As shown in FIG. 4, the function generator 17 consists of fixed resistors R ₁ , R ₂ , variable resistor R ₃ , and an operational amplifier IC, and is connected to the downstream power station PS2 corresponding to the guide vane opening η ₁ of the upstream power station PS1. Guide vane opening degree η ₂
This outputs the following. Further, the converter 18 converts the flow rate Q ₁ flowing into the regulating reservoir 1 into the guide vane opening degree η ₁ of the upstream power plant PS 1, and the function generator 17
This is what is output to.

It is now assumed that the relationship between the water turbine flow rate Q ₁ of the upstream power plant PS1 and the guide vane opening signal η ₁ of that water turbine is expressed by equation (6).

η ₁ = i (Q ₁ ) ...(6) Also, the relationship between the flow rate Q ₃ of the water control car in the downstream power station PS2 and the guide vane opening signal η ₂ of the water control car in the downstream power station PS2 is (7)
It shall be shown by the formula.

η ₂ = f ₂ (Q ₃ ) ...(7) In this case, the adder 16 is set so that Q ₁ = Q ₃ during steady water conditioning operation, that is, within the entire range of the rated flow rate of the water conditioning vehicle. Create a characteristic of the function generator such that the output becomes zero. For simplicity, for example η ₁ ,
Assume that η ₂ is expressed by equations (8) and (9).

η ₁ = a ₁ Q ₁ + b ₁ ...(8) η ₂ = a ₂ Q ₃ + b ₂ ... (9) Here, a ₁ , b ₁ , a ₂ , b ₂ are constants, and a ₁ , b ₁ ,
a ₂ , b ₂ , Q ₁ and Q ₂ are positive numbers. On a regular basis
So that Q ₁ = Q ₃ (=Q ₂ ), that is, the input/output characteristic k of the function generator 17 is k=a ₂ /a ₁・η ₁ +(b ₂ −a ₂ /a ₁ b ₁ )...
…(10).

Here, when the flow rate Q ₁ of the upstream power station PS1 is the guide vane opening degree η ₁ , the flow rate Q ₃ of the downstream power station PS2 is Q ₃ =Q ₁ . Further, the guide vane opening degree of the downstream power station PS2 at that time is η ₂ , and the output k of the function generator 17 is (k=η ₂ ).
In other words, the output of adder 16 is zero.

In this state, the flow rate of upstream power station PS1 is now Q ₁
Suppose that +△Q ₁ . Then converter 1
8 outputs the guide vane opening degree η ₁ +Δη ₁ corresponding to the flow rate Q ₁ +ΔQ ₁ . Function generator 17
When this guide vane opening degree η ₁ +Δη ₁ is input, the following ′k is outputted from equation (10).

′k=a ₂ /a ₁・(η ₁ +△η ₁ )+(b ₂ −a
₂ /a ₁ b ₁ )... (11) That is, the output of the function generator 17 is ('k-
k=a ₂ /a ₁ ·Δη ₁ ). At this point, the water level h ₁ of the regulating pond 1 does not increase rapidly due to the time constant T ₁ , so the guide vane opening degree of the downstream power plant still shows a value approximately equal to η ₂ .
Therefore, the adder 16 outputs a value a ₂ /a ₁ ·Δη ₁ corresponding to the increase in the output of the function generator 17. As a result, the guide vane opening degree of the downstream power plant PS2 is controlled in advance.

In this way, the water level adjustment device 11 according to the present invention
The function generator 17 receives the guide vane opening of the water turbine of the upstream power station PS1, which corresponds to the inflow rate _Q1 from the upstream power station PS1, and generates the flow rate corresponding to the inflow rate _Q1 to the downstream power station PS2. The adder 16 calculates the correction amount for the guide vane opening of the downstream power plant PS ₂ so that the water flows out from the water control car, and the guide vanes of the water control car are opened and closed in advance according to the polarity of the adder 16. I'll do what I do.

In other words, when the inflow amount QA to the regulating pond 1 changes, with the conventional water level regulating device, the water level remains stable with a deviation in the regulating pond water level _h1 due to the delay in phenomena in the water channel system. However, according to the present invention, this deviation hardly occurs. slightly function generator 17
Only the amount corresponding to the deviation in accuracy occurs.
This is based on the output of the function generator 17, which changes the opening of the guide vane of the downstream power plant PS ₂ in advance and adjusts the inflow amount Q ₁
This is because the control is performed so that the outflow amount Q 3 and the outflow amount Q ₃ are equal to each other.

In the conventional water level adjustment device, the allowable deviation of the water level _h1 of the regulating pond is only allowed by the water level adjustment rate determined from stability as described above, but in the present invention, the deviation is Since this rarely occurs, it is possible to automatically control the output (flow rate Q ₃ ) of the water control vehicle according to the inflow amount Q ₁ even if the water depth of the regulating pond cannot be greater than the water level adjustment rate.

Next, in the embodiment shown in FIG. 3, the flow rate Q ₁ is expressed by the guide vane signal η ₁ , but the function generator is configured to express the flow rate Q ₁ by the generator output [MW], pressure, water level, etc. Similar effects can be obtained even if the

In the present invention, as described above, the water level adjustment device is configured to use the control signal from the upstream power plant as an auxiliary signal, so that operation can be ensured with an operating water level width greater than the water level adjustment rate. In other words, stable water conditioning operation can be performed over the entire range of the water conditioning vehicle. Furthermore, since the water level deviation can be reduced, the water turbine can be operated at a high water level in the regulating pond and the efficiency of the water turbine can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a waterway system to which the present invention is applied, FIG. 2 is a conventional water level adjustment control block diagram, and FIG. 3 is a water level adjustment control block diagram of the present invention.
FIG. 4 is a circuit diagram showing an example of a function generator used in the present invention. PS1...upstream power plant, 1...regulating pond, 2...pressure headrace, 3...surge tank, 4...pressure iron pipe, PS2
...Downstream power plant, 11...Water level adjustment device, 12...Incomplete differentiation circuit, 13, 14, 16...Adder, 15...
2 transfer function, 17...function generator, 18...converter.

Claims (1)

[Claims] 1. Control the guide vanes of the water turbines of the downstream power plant based on the deviation between the water level of the regulating pond and its reference water level so that the same flow rate as the inflow flowing into the regulating pond from the upstream power plant flows out to the downstream power plant. In the water level adjustment device, the function calculates the opening degree of a guide vane of a water turbine of the downstream power station in order to cause the same flow rate to flow out to the downstream power station based on the inflow amount flowing into the regulating pond from the upstream power station. A generator and an adder for obtaining the deviation between the guide vane opening obtained by this function generator and the actual guide vane opening of the water turbine of the downstream power plant are provided, and the deviation obtained by this adder is added to the downstream power plant. A water level adjustment device characterized in that it is used as an auxiliary signal for guide vane control of a water turbine in a power plant.