JPS6355372A - Operation control method for variable speed hydraulic power station - Google Patents

Abstract

PURPOSE:To prevent a trouble caused in use of an electric power system in advance, by producing a rotating speed increase command or a rotating speed decrease command when outputs from respective generators are greater than a set upper limit output or less than a set lower limit output. CONSTITUTION:A generator output sensor 11 provided with a generator 10 produces a rotating speed increase command or a rotating speed decrease command when an output from the generator 10 is greater than a set upper limit output or less than a set lower limit output. With the arrangement, a turbine is prevented from being in motor operation or in excessively loaded operation when operation of the other generator is changed so that the turbine and facilities provided with it are prevented from being damaged by an abnormal operating condition, whereby a trouble caused in use of an electric power system can be prevented in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for controlling the operation of a hydroelectric power generation device capable of variable speed operation of a water turbine or a pump water turbine (hereinafter simply referred to as a water turbine).

(Prior Art) A hydroelectric power generation device consisting of a water turbine and a generator or generator motor (hereinafter simply referred to as a generator) directly connected to the water turbine is as follows:
Except for some low-head machines, they are often installed in long waterways.

When installing multiple water turbines on such a long waterway, in order to reduce the civil engineering costs required for waterway construction, the waterway from the upper pond to the branch point in the middle is made into a single pipe common to all the water turbines. In many cases, the waterway from the branch part to the lower pond via each water turbine is constructed from a plurality of branch pipes.

Figure 6 shows the schematic configuration of a hydroelectric power plant equipped with two branch pipes. Branch pipes 5a and 5b are established between the part #1 section 3 and each of the water turbines 5a and 5b, and the water that has finished its work in each of the water turbines 5a and 5b is drained to a drainage pipe 7a.
, 7b and then sent to Shimoike 2. In addition, a surge tank 8 is installed near the branch 3 to suppress water pressure fluctuations in the pipeline.
is installed.

The hydroelectric power plant configured as described above has a drawback in that a change in the operating state of one water turbine affects the other water turbines.

That is, for example, in the hydroelectric power plant shown in Fig. 6, when one of the - water turbines 5a is in power generation operation and the other water turbine 5b is in operation with no load opening, based on a request from the power system, When the water mouth opening of the water turbine 5b is opened in order to shift the water turbine 5b that is in standby operation to power generation operation, the water turbine 5 that is in power generation operation changes.
The output of the water turbine a suddenly decreases, and depending on the case, the motor runs, and even though the grid is requesting electricity, it consumes electricity from the grid, which can have a negative impact on the grid.

The manner in which the operating state changes at this time will be explained with reference to FIG. In the figure, the own machine corresponds to the water turbine 5a in FIG. 6, and the other machines correspond to the water turbine 5b in FIG.

In order to shift the other units from standby operation to power generation operation, when the water mouth opening a2 of the other units starts to open at time To, the other units 5b
Since the flow rate of the side pipe 6b increases rapidly, the water level W of the surge tank 8 decreases from the initial water level Wso as shown in FIG.

In this case, the water port opening of No. 1 115a during power generation operation a 1
Both rotational speeds N1 are constant, but the effective head H of the water turbine
As shown in FIG. 6, is approximately equal to the difference between the water level of the surge tank 8 and the water level of the lower pond 2, so the water level W of the surge tank
When s decreases, the effective head H of the water turbine also decreases, and therefore the output of the water turbine in the lower pond changes as shown by the curve P1 in FIG. 7 after time To. That is, the water turbine output P becomes zero at time T1, and becomes the minimum output (negative output in this case) at time T2.

From time T2, the water level of the surge tank changes to W, so the water turbine output P1 also increases, becomes a positive output at time T3, and returns to the initial output P1i1. at time T4. : Although the water returns to normal, the surge tank water level W continues to rise for a while, so the water turbine output P1 also increases further, reaching a high level at time T5. After that, the water turbine output P of the own unit will be adjusted according to the water level photography of the surge tank.
1 will gradually converge toward a new steady state.

As mentioned above, a water turbine installed in a branch pipe connected to a single pipeline and generating electricity (self-number unit) is a water turbine installed in another branch pipe connected to the same pipeline (other unit). When transitioning from standby operation to power generation operation, the water turbine output of the own unit was reduced due to the influence of the water mouth opening, and at time T.
1 to T3, the motor operates and consumes power from the grid.

The cause of this phenomenon can also be explained from the torque characteristics of the water turbine shown in FIG.

The curves m, m, and m3 in Fig. 8 represent the generated torque of the water turbine as To, the effective head at that time as H, and the rotational speed as N.
We have shown how T/H changes with respect to N/m using the water mouth opening a1 of the own machine as a parameter, so T - T6 in the figure corresponds to T - T6 in Fig. 7, respectively. ing.

In the same figure, the operating state of the lower pond where the water mouth opening degree a1 is constant changes on the curve m2, but at time T. When the surge tank water level W decreases from the initial state (indicated by ◎), the effective head H of the turbine also decreases, so the operating point changes in the direction of increasing The value of /H becomes small, and at time T1, T/H=O, and the water turbine output becomes zero.

After time T1, the effective head H of the water turbine further decreases, so the torque T of the water turbine becomes negative, and power from the grid is consumed. The time T2 at which N/E■r is maximum is the seventh
This corresponds to the lowest water turbine output point in the figure.

After time T2, the effective head H of the water turbine increases, so the operating point moves in the direction in which N/J'Ttfi decreases, and at T3.
The water turbine output P1 reaches a maximum point T5 via T4.

As mentioned above, the water turbine is operated with negative torque between times T1 and T3, but in this negative torque region, vibration and cavitation increase, which may cause damage to the water turbine and its attached mechanisms. As mentioned above, there is a serious drawback in that even though the grid requests power supply, it ends up consuming power.

In addition, in the above explanation, we have explained the case where the water mouth opening of the own machine does not change and the water mouth opening of other machines opens, but even if the water mouth opening of the own machine suddenly opens, the water level of the surge tank will change. changes, a phenomenon similar to the above occurs.

Next, with reference to FIGS. 9 and 10, a phenomenon will be described in which a load shedding occurs in the other machine while both the own machine and the other machine are in power generation operation, and the water mouth opening is made to be fully opened.

In Fig. 9, when a load 'llX% occurs in another machine at time To and its water port opening a2 rapidly closes, the flow of water flowing through the ° branch pipe 6b in Fig. 6 decreases. ,
The water level W in the surge tank rises rapidly as shown in FIG.

Therefore, the water turbine output P1 of the own machine (5a in Fig. 6) is the water turbine opening a1. The rotational speed N1 increases even though it does not change, and the water level W8 of the surge tank becomes the initial water level Ws.
During times T1 to T3, when the output is significantly higher than o, the water turbine is operated at exceeding its rated maximum output.

Figure 10 explains how many times the phenomenon shown in Figure 9 occurs from the torque characteristics of the water turbine.
1 is constant, when the effective head H of the water turbine increases, the operating point moves on the curve m3 in the direction where N/4 H- decreases, T/H increases, and the value of torque T also increases as the effective head increases. It can be seen that the value increases as H increases.

By the way, in recent years, with the advancement of semiconductor I and Ill element circuit technology, variable speed hydropower generation has been developed that allows the rotational speed of the water turbine to be arbitrarily changed over a wide range by controlling the winding induction power generation sensor with a cycloconverter device. The device has started to attract attention.

In such variable speed hydroelectric power generation equipment, the water levels of the upper and lower reservoirs are measured to determine the effective head that acts on the water wheel, and the rotational speed of the water wheel is controlled according to this effective head to keep the water wheel at a constant high level. Control methods for efficient operation have been proposed (for example, Japanese Patent Application Laid-open Nos. 48-21045 and 57-
No. 113'971, etc.).

According to such an operation control method, by changing the rotational speed of the water turbine according to the head, the water turbine can be operated stably and with high efficiency no matter the head. However, as explained in Figures 7 and 9, if the effective head of the turbine changes due to transient changes in the waterway system, even if a variable speed turbine is used,
As long as conventional operation control methods are used, they perform only as poorly as they would in water at a constant rotational speed.

(Problems to be Solved by the Invention) As mentioned above, in a water turbine installed in a branch pipe connected to a common straight pipe, the water turbine may switch to motor operation due to a sudden change in the operating status of other units or the own unit. Conventional operation control methods have not been able to take effective countermeasures against this problem, even for water turbines that can operate at variable speeds.

In addition, a method of adjusting the water mouth opening of the own unit in response to motor operation or overload operation may be considered, but sudden changes in the water mouth opening will encourage surging, and the operating condition of the water turbine will instead deteriorate. It has not been put into practical use because of the high risk of

[Structure of the invention]

(Means for Solving the Problems) The present invention has been made to eliminate the above-mentioned drawbacks in the background art, and a variable speed hydroelectric power generation device is installed in multiple branch pipes branching from a single pipe pipe. At a hydroelectric power plant, 5 each! The output of the electric machine is detected by a generator output detector, and when this detected value exceeds the set upper limit output or falls below the set lower limit output, a rotation speed increase command or rotation speed decrease command is output to control the hydraulic power generation equipment. It is characterized by changing the target rotation speed.

(Function) In the operation control method of the present invention configured as described above, when the generator output exceeds the set upper limit output or the set lower limit output, the rotation speed increase command or the rotation speed decrease command is given priority to the rotation speed. Since the rotational speed of the generator is controlled by the speed control device, it is possible to prevent the water turbine from falling into motor operation or overload operation even if the operating conditions of other units or the own unit suddenly change.

In other words, the horizontal axis coordinate N/fl in Figures 8 and 10
Changes in the operating point of the water turbine can be reduced, and the amount of deviation of the generator output from the upper and lower limits can be reduced, and troubles in power system operation can be prevented.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

In Fig. 1, the upper end of the pipe 6 is connected to the single-line pipe 4 explained in Fig. 6, and the lower end of the drainage pipe connected to the discharge side of the water turbine 5 leads to the lower pond. .

Power generation Ifi1 is connected to the main shaft of the water turbine 5 via a coupling 9.
0 is directly connected. A wound induction generator capable of variable speed operation is normally used as this generator, and its output is connected to the power system via a cycloconverter device (not shown) or the like.

The generator 10 includes a generator output detector 1 for detecting its output.
1 is installed, and the generator output P1 output from this generator output detector is led to a comparator 12 and compared with the set upper limit output PH to produce a deviation value ΔP, which is also led to a comparator 13. It is compared with the set lower limit output P and the deviation value Δ
produces P. These deviation values ΔP and deviation values Δ
P.

■ are upper limit output detectors 14 and 14, respectively. It is led to the lower limit output detector 15.

The upper limit output detector 14 outputs the rotation speed increase command N0 when ΔP0 is positive, that is, when the generator output signal P1 exceeds the set upper limit output P. In addition, the lower limit output detector 1
5 outputs a rotational speed reduction command NL when △PL is negative, that is, when the charger output signal @PS falls below the set lower limit output PL.

On the other hand, the required output P1, the water opening a, the water level W, etc. are input to the rotation speed setter 16 which sets the normal rotation speed of the generator 10, and outputs the optimum rotation speed N.

pt This optimum rotation speed I! ! NOPt, the above-mentioned rotational speed increase command N and rotational speed decrease command N are input to the target rotational speed/slowdown setter 17, which outputs the target rotational speed NQ.

The rotational speed control device 18 has a target rotational speed N. is input, and the generator 10 is controlled to reach its target rotation speed.

The above-mentioned target rotation speed setting device 17 is always set to the optimum rotation speed N.
is the target rotational speed N. Bind and output. pt is the rotation speed increase command Nl or rotation speed decrease command NL
It has a function that prioritizes those signals when they are input.

Rotation speed increase command N for the above-mentioned ΔPl+ and ΔP[
The value of H or rotational speed reduction command N [is generally ΔP
The bright part is formed by a combination of the proportional value, differential value, and integral value of □ and ΔP. That is, ′ □N)l”A11×Δp
H+B, Xd/dt <Δp,, >+CxfΔp d
t - (1) II ) 1 ~ = AL x ΔP1 + BL xd/d t (ΔP1
)+CxfΔp dt −(2) L L . In these equations, A, B, C, , H AL, B , C are constants set according to various factors such as the characteristics of the water turbine, the time constant of the rotating body, and the inertia of the water in the pipe. It is.

Although the above equations (1) and (2) are theoretical, in practice it is often difficult to accurately determine the value of each constant. In such a case, in practice, the upper limit value N and the lower limit value N of the rotational speed for power generation that can be actually operated are determined due to the limitations of the ability of the cycloconverter device etc. that converts the frequency of the generator 10. m
+ n, so when Δp > o: N,, = Nlax ・ (3) Δ
When P ku0: NL=N (4) If
rn + n as above (1), (
2) may be used instead of Eq.

In the operation and control device for the variable speed hydroelectric power generation device configured as described above, the output P of the generator 10 is set to the upper limit output Δ.
When the value is between PH and the set lower limit output ΔP[, the upper limit output detector 14 and the lower limit output detector 15 do not produce outputs N, N, so the target rotation speed position setting device 17 sets the rotation speed. signal N from device 16
The same target rotational speed N. is outputted to the rotational speed control device 18, and the generator 10 is controlled to reach the target rotational speed.

In such a situation, for example, if the water inlet opening of another unit in standby operation suddenly opens due to a command from the grid, and the generator output P1 of the own unit falls below the set lower value output P, the operation will be activated. Shown in Figure 2.

In the figure, when the water port opening a2 of the other unit starts to open at time To, the water level W3 of the surge tank and the water turbine output (-generator output) Pl of the own unit decrease for the same reason as explained with reference to Figure 2. Begin to.

At time T1, when the water turbine output P1 of the own unit falls below the set lower limit output PL, the lower limit output detector 15 is activated and a rotation speed reduction command N is output, whereby the output of the target rotation speed setting device 17 is Minimum rotational speed M at time T
(When using the above-mentioned (4) 1 man formula).

As a result, the rotational speed control device 18 starts controlling the rotational speed of the water turbine to become N. However, the actual rotational speed of 1n gradually decreases as shown by the curve N due to the influence of the time constant of the rotating body. do.

In this case, since the rotation speed is lower, the water turbine output of the own machine becomes slower than in the case of FIG. 7 where the rotation speed is constant, and the lowest value of the water turbine output P1 does not become a negative output.

The reason for this is explained based on the torque characteristics shown in Figure 3.
When the surge tank water level decreases at time To, the effective head H of the water turbine also decreases, so the operating point of the water turbine moves in the direction of increasing N/n on the curve m2.

However, after time T1, the lower limit output detector 15 operates and the rotational speed N of the water turbine decreases, so the effective groove ffH
Even if N/VmT7) decreases greatly, the decrease is slight until time T, and the torque T/H decreases from the lowest output point (T)t to
will be kept in the positive region.

Next, in the operation control method of the present invention, the operation when the water mouth opening of other units suddenly decreases and the generator output of the lower pond exceeds the set lower limit output PH is shown in Figs. 4 and 5. I will explain.

When the water port opening a2 of other units begins to decrease rapidly at time T due to load shedding, etc., the surge tank water level W
increases, and the generator output P of the own unit also increases. When the generator output P1 exceeds the set upper limit output P□ at time T1, the upper limit output detector 14 is activated and a rotational speed increase command N)l is issued. As a result, the output N of the target rotation speed setter 17 becomes the maximum rotation speed N at time T.
(=N), but the actual water turbine rotation speed N1
Due to the influence of the time constant of the rotating body, as shown by curve N in FIG. 4, it rises slowly after time 1.

In this way, in the present invention, the rotation speed of the own water turbine increases, so the output of the water turbine is equal to that of the 9th turbine whose rotation speed is constant.
It is slower than the case shown in the figure, and its maximum □ output value is also kept low.

To explain the reason with reference to No. 5-, the time To-T
Since the rotation speed is constant during 1, the water level of the surge tank W
The operating point of the water turbine moves in the direction of N/('Tnfi small) by the increase in the effective head H due to the upper limit of 8. However, after time T1, the upper limit output detector 14 is activated as described above. Therefore, even if the effective head H increases, the operating point N/E■1 does not decrease much compared to the case where the rotation speed is constant, and as a result, the torque of the water turbine does not increase much. First, the increase in water turbine output will be suppressed.

As is clear from the above explanation, in the operation control method of the present invention, the power generation output P is detected, and when it exceeds the set upper limit output PH or falls below the set lower limit output P, The target rotation speed N is achieved by outputting the rotation speed increase command Ni1 or the rotation speed decrease command N. This makes it possible to maintain the output of the water turbine and, in turn, the generator, within a small range of fluctuation, and prevents the water turbine from operating under motor conditions that consume power from the grid, or under overload conditions that exceed the maximum rated output. You can avoid falling into it.

〔Effect of the invention〕

As described above, according to the operation control method of the present invention, it is possible to prevent the water turbine from falling into motor operation or overload operation when the operation of the signal is changed, thereby preventing damage to the water turbine itself or its auxiliary equipment due to abnormal operating conditions. It is also possible to prevent troubles in power system operation from occurring.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the operation control method of a variable speed hydroelectric power generation device of the present invention, FIGS. 2 to 5 are operation explanatory diagrams and torque characteristic diagrams showing the operation, and FIG. 2 on the road
FIGS. 7 to 10 are operation explanatory diagrams and torque characteristic diagrams showing the operation of a conventional hydraulic power generation system. 1... Upper pond, 2... Lower pond, 3... Branch, 4...
・Single pipeline, 5.5a...Waterwheel, 6.6a, 6b...
- Pipes, 7.7a, 7b...Drainage pipes, 8...Surge tank. Applicant's agent Mr. Sato Figure 1 Figure 2 Figure 5 Time T Figure 7 □ Figure 8 Time T Figure 9

Claims (1)

[Scope of Claims] 1. In a hydroelectric power plant in which a variable speed hydroelectric power generation device is installed in a plurality of branch pipes branching from a single pipe, the output of each generator is detected by a generator output detector; Variable speed hydraulic power, characterized in that when a detected value exceeds a set upper limit output or falls below a set lower limit output, a rotation speed increase command or a rotation speed decrease command is output to change the target rotation speed of the hydroelectric power generation device. Operation control method for power generation equipment. 2. Input the generator output and the set upper limit output to a comparator and compare them, guide their deviation value to the upper limit output detector to output a rotation speed increase command, and also input the generator output and the set lower limit output. are input into a comparator and compared, their deviation values are led to a lower limit output detector to output rotation speed reduction commands, and these commands are used to change the target rotation speed of a hydroelectric power generation device. A method for controlling the operation of a variable speed hydroelectric power generation device according to claim 1.