JPH086679B2 - Control method for variable speed hydropower plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a hydroelectric power generation facility equipped with a water turbine and a generator capable of variable speed operation, in a quick manner with respect to load fluctuation, and in addition to a water channel. The present invention relates to a control method for a variable speed operation hydroelectric power generation facility that can respond without adversely affecting the system.

In a hydroelectric power plant, so-called AFC operation in which the output of the power plant is changed based on an output command may be performed for the purpose of stabilizing and adjusting the power system.

This AFC operation is performed by opening and closing the guide vanes of the turbine in accordance with the output command from the command station in the hydroelectric power generation equipment that consists of a synchronous generator and a turbine that is directly connected to it and rotates at a constant rotation speed. Came.

That is, as shown in FIG. 7, when the AFC operation command is input, the load fluctuation range ΔP, as shown in FIG.
When it fluctuates in the fluctuation cycle f, the guide vane opening degree correspondingly changes as shown in FIG.

However, in such an operation control method, when the opening / closing speed of the guide vane is fast, surging occurs in the water channel system due to the water hammer effect accompanying the change in the turbine flow rate, and the water pressure of the penstock connected to the inlet side of the turbine is increased. As shown in FIG. 7 (c), there is a large fluctuation and the risk of breakage increases. For this reason, in the hydroelectric power generation facility operated at a constant rotation speed as shown in FIG. 6D, it is impossible to perform the AFC operation when the target output changes at high speed.

On the other hand, recently, variable-speed operation hydroelectric power generation equipment that employs a wound-rotor induction generator instead of a synchronous generator has come to be widely used. In this variable speed operation hydroelectric power generation facility, the output of the generator can be changed at high speed by adjusting the amount of excitation of the wire wound induction generator without adjusting the guide vane opening. Therefore, from the point where the guide vane opening does not change in this variable speed operation hydroelectric power generation facility,
The above-mentioned water hammer effect does not cause the problem of surging of the pipeline system, and high-speed AFC operation becomes possible.

However, even in such a variable-speed operation hydroelectric power generation facility, high-speed AF can be performed simply by adjusting the excitation amount of the wire wound induction generator.
When trying to perform C operation, the following problems occur.

That is, as shown in FIG. 8 (a), the response of hydraulic turbine and generator as an example a case where the target generator output P ^* is changed stepwise from P ₀ ^* to P ₁ ^* at a time t ₀ Description Then, since the excitation amount is adjusted instantaneously, the generator output Pg immediately changes so as to match the target generator output P ^* , as shown in FIG.

As a result, as shown in FIG. 8 (e), the generator torque Mg and the turbine torque Mt are such that the generator torque Mg> the turbine torque Mt after the time t ₀ . as shown in), gradually decreases from N _o.

In the variable-speed operation hydroelectric power generation facility, the turbine rotation speed N
If the output voltage of the thyristor changes, the thyristor converter controls the output frequency of the generator to match the frequency of the grid. It is not possible to deal with a large output fluctuation exceeding the range by only controlling the excitation amount of the wound-rotor induction generator.

That is, as shown in FIG. 8 (d), the turbine rotation speed N
There was gradually reduced from No, through the rotational speed N ₁ at time t _1, and the near Nuisance to the lower limit rotation speed which can be converted in a thyristor, the opening command to the guide vanes is emitted it as a condition, FIG. (C ), The guide vane opening a is a ₀
Open from. Thus waterwheel torque Mt is rapidly increased, since the time t ₂ the water wheel torque Mt> generator torque Mg, water turbine rotational speed N is turned upward, becomes stable soon at the new rotational speed N ₁ .

However, during that time, the guide vane opening degree changes from a ₀ to a ₁
Even if it is a water turbine that can operate at variable speed,
A sudden change in output cannot be followed up due to the problem of the pipeline system as in the conventional turbine with a constant rotation speed.

Next, the response process described above will be examined on the characteristic curve of the water turbine shown in FIG. In the figure, the thick solid line connecting the points X ₀ , Xm, and X ₁ shows the locus of motion of the water turbine from time t ₀ to t ₁ and then to t ₂ , and the curves a ₁ , a ₂ , a ₃ , a ₄ is the guide vane opening a ₁ , a ₂ , a
₃ shows the relationship between water turbine rotational speed N and the hydraulic turbine output Pt at each time point of a _4.

In the figure, chain lines η ₁ , η ₂ , η ₃ and η ₄ are isoefficiency curves,
The curve Lopt connects the maximum efficiency points at each guide vane opening.

As described with reference to FIG. 8, the guide vane opening is constant from time t ₀ to t ₁ , and the turbine rotation speed N decreases.
As shown in Fig. 9, the turbine output Pt also increases due to the decrease in the turbine rotation speed N. This is due to the turbine torque in Fig. 8.
It corresponds to the increase of Mt. Further, the operating point of the water wheel rotation speed N at time t ₁ of Figure 8 is N <N ₁ corresponds to the Xm point Figure 9.

In Figure 9, the variable speed operation can be water turbine, water turbine output Pt and the guide vane opening a ₁ operating point in response to ~a ₄ curve Lo
By adjusting the water turbine rotational speed N to come on pt, always can be operated water turbine at maximum efficiency, only relative sudden change in the target generator output P ^* as shown in FIG. 8 In the control method of adjusting the generator output by changing the amount of excitation of the wound-rotor induction generator, the operating point deviates from the maximum efficiency curve as shown in FIG.

Further, as shown in JP-A-59-72998, the operating point is always on the maximum efficiency curve Lopt by changing both the guide vane opening and the turbine rotation speed N with respect to the target generator output P ^* . There is also a known method of controlling so that the turbine output Pt does not change until the guide vane opening changes, no matter how quickly the amount of excitation of the generator is adjusted. The followability of the generator output with respect to the generator output P ^* depends on the changing speed of the guide vane opening. Therefore, even in this method, as in the conventional water turbine that operates at a constant rotation speed, there arises a problem such as urging in the pipe system in response to a sudden output change request.

(Problems to be solved by the invention) As described above, in the AFC operation in which the generator output is changed with time, the water turbine that is operated at a constant rotation speed is abrupt in consideration of the water hammer effect of the pipeline system. Since the change in the guide vane opening is limited, it is not possible to follow the AFC operation in which the target output change speed is fast.

On the other hand, in a water turbine that can be operated at variable speed, the generator output can be changed at high speed without changing the guide vane opening of the water turbine by adjusting the amount of excitation of the wound-rotor induction generator. Is possible. However, even in a generator capable of variable speed operation, the range of rotational speed at which variable speed operation is possible is limited by the capacity of the thyristor converter. Since it is out of the possible range, it is impossible to deal with the change in the target output only by changing the excitation amount. In such a case, it is necessary to change the guide vane opening degree and adjust the output, so that it is not possible to cope with high-speed AFC operation as in the conventional turbine driven at a constant rotation speed.

Further, in a water turbine that can be operated at a variable speed, both the guide vane opening and the turbine rotation speed are changed with respect to the target output, and the operating point that maximizes the efficiency with respect to the output at that time is selected and operated. However, as described above, if the amount of excitation is simply changed with respect to the change in the target output, the operating point deviates from the maximum efficiency point.

On the other hand, if both the turbine rotation speed and the guide vane opening are controlled, the operating point can be set to the highest efficiency point at the guide vane opening, no matter how the target output changes. Since the changing speed of is the same as the changing speed of the guide vanes, it cannot support high-speed AFC operation as well as the above-mentioned water turbine that operates at a constant rotation speed.

(Object of the Invention) The present invention has been made to eliminate the above-mentioned drawbacks in the background art, and is provided with a water turbine and a generator that operate at variable speeds, and a control device thereof, and for a given head and target output. By adjusting both the guide vane opening and the turbine speed, the variable-speed operation hydroelectric power plant that can operate the turbine under the operating conditions that maximizes the turbine efficiency can be operated at high speed by changing the generator output at high speed. An object is to provide an operation control method that enables the operation.

[Structure of Invention]

(Means for Solving Problems) In the control method for a variable speed operation hydroelectric power generation facility according to the present invention, a turbine and a rotational speed connected to the turbine can be set to an arbitrary value within a predetermined range. In a variable-speed operation hydroelectric power generation facility including a variable-speed generator and its control device, a target generator output P ^* or a difference ΔP ^* between this P ^* and an actual generator output Pg is used as a low-speed component by a filter circuit. And the high speed component, the guide vane of the water turbine is controlled by the low speed component, and the rotation speed of the variable speed generator is controlled by the high speed component.

(Operation) According to the control method of the variable speed operation hydroelectric power generation facility of the present invention configured as described above, the slow target generator output P
^With respect to the change of ^*, the generator output can be adjusted by changing the guide vane opening degree by the low speed operation command Ps, like the conventional water turbine without a variable speed device. On the other hand, for the high speed target generator output P ^* , a low speed operation command is issued.
Since Ps does not change, the generator output can be adjusted by changing the rotation speed of the generator according to the high speed operation command Pf. In this case, since the guide vanes hardly move, no matter how fast the target generator output P ^* changes, the water hammer phenomenon of the pipe system is not induced.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a generator 1 is a wire-wound induction generator and is directly connected to a water turbine runner 2. The water turbine has a movable guide vane 3, and the flow rate flowing into the water turbine runner 2 can be adjusted. The variable speed device 4 adjusts the amount of excitation of the generator 1 so that its input becomes zero, and controls its output or rotation speed.

In the AFC operation, the target generator output P ^* is input to the filter circuit 5 to obtain the low speed operation command Ps from which the high speed component is removed. On the other hand, to obtain a target generator output ^{P *} and high-speed operation command from the difference ^{_{Ps P f (= P * -Ps}} ).

The opening degree setting device 6 obtains the optimum guide vane opening degree a ^* from the driving head H of the turbine at that time and the low speed operation command Ps. The guide vane controller 7 to which the guide vane opening a ^* is input controls the guide vane 3 so that the opening a of the guide vane 3 of the water turbine matches the a ^* .

On the other hand, the high speed operation command device 8 outputs the variable speed signal ΔP based on the value of the high speed operation command P _f (ΔP = Pf). The variable speed device 4 changes the excitation amount of the generator by this ΔP. In addition, the high-efficiency operation commander 9 uses the guide vane opening a and the head H of the turbine.
The rotation speed N ^{* at} which the turbine efficiency is the highest is calculated.
The difference ΔN between this N ^* and the actual rotational speed N of the water turbine is also input to the variable speed device 4 described above, and the amount of excitation of the generator is also adjusted according to the value of ΔN.

FIG. 2 shows the response of an embodiment of the present invention when the target generator output P ^* changes from P ₀ ^* to P ₁ ^* at time t ₀ in the variable speed operation hydroelectric power generation facility having such a configuration.

When the target generator P ^* changes stepwise as shown in FIG. 7A at time t ₀ , the low speed operation command Ps which is the output of the filter circuit changes slowly as shown by the solid line in FIG.

Therefore, the high-speed operation command Pf, which is the difference between the target generator output P ^* and the low-speed operation command Ps, is indicated by the time as shown by the chain line in FIG.
It stands up momentarily at t ₀ . Since this value is input to the variable speed device 4 as ΔP, the amount of excitation of the generator 1 changes instantaneously, and the generator output Pg substantially matches the target value P ^* . However,
At this time, as for the torque of the generator 1, Mg rapidly increases as shown by the solid line in FIG. 6 (f) and exceeds the torque Mt generated by the water turbine.
The rotation speed N of the water turbine decreases as shown by the solid line in FIG.

On the other hand, at this time, the guide vane 3 of the water turbine has a low speed operation command Ps.
Since it is controlled by, the opening gradually starts as shown in FIG. Therefore, the torque generated by the water turbine
Mt also increases with time, and exceeds the generator torque Mg at time t ₁ . Therefore, after the time t ₁ , the rotation speed N of the water turbine changes once and changes in an increasing direction. The time t ₂ at a low speed operation command Ps is equivalent to the value of the target generator output P ^*.

During this period, the high-efficiency operation commander 9 calculates the optimum (target) turbine rotational speed N ^* from the guide vane opening a and the operation head H of the turbine. Since this N ^* changes as shown by the chain line in FIG. 2 (e), a rotation speed increasing command is input to the variable speed device 4, and after time t ₁ when the high speed operation command Pf becomes small, adjustment of the amount of excitation so as to increase the rotational speed is performed, the final rotational speed of the water wheel at time t ₂ is consistent with the new target rotational speed N _1.

FIG. 3 shows changes in the turbine operating point in the above control process. The definitions of the curves a _{1 to} a ₄ and η _{1 to} η ₄ are the same as in FIG. 9 described above. The operating point X ₀ corresponds to the operating point at time t ₀ . The operating point at which the rotation speed N becomes the minimum at time t ₁ is point Xm, and the final operating point at time t ₂ is X ₁ .

As described above, according to the operation control method of the present invention, not only can a rapid change in the target output be quickly responded, but finally, the operating point of the hydraulic turbine (the curve Lopt
You can take it to the above).

4 and 5 show how the above-described embodiment of the present invention responds to a slow change in the target output and a rapid change in the target output. The variables represented by the lines in the figure are the same as in FIG.

Figure 4 is intended to show the response to the target output P ^* of the changes slowly, the change in the P ^* is gradually as in this case the figure (a), low-speed operation command Ps is the target generator output It almost agrees with P ^* . Therefore, high-speed operation command
Pf becomes almost zero as shown by the chain line in FIG.
The output ΔP of the high speed operation command device 8 in FIG. 1 is also substantially zero.

For this reason, the adjustment of the excitation amount of the generator 1 requires the target rotation speed N.
The difference ΔN between ^* and the actual rotation speed N is controlled to zero. As a result, the rotation speed N changes very slightly as shown in FIG. 4 (e), and the operating point of the water turbine comes to the high efficiency band shown by the curve Lopt in FIG. On the other hand, the guide vane opening a is controlled based on the low speed operation command Ps in FIG. 7C, and the generator output Pg also changes as shown in FIG.

FIG. 5 shows the response to a rapid change in the target output P ^* .

In this case, since the change in P ^* is large and fast as shown in FIG. 5 (a), the low speed operation command Ps which is the output of the filter circuit becomes P ^* as shown by the solid line in FIG. 5 (c). The signal is significantly attenuated in comparison. Therefore, P ^* and Ps
The high-speed operation command Pf, which is the difference between
Greater than Ps.

As a result, since the variable device 4 is controlled based on the high speed operation command Pf, the generator output Pg substantially matches the target output P ^* as shown in FIG. 5 (b), and the rotational speed N of the water turbine is the generator torque.
The difference between Mg and the water wheel torque Mt changes as shown in FIG.

On the other hand, since the guide vane opening a is controlled based on the low speed operation command Ps, it only slightly changes as shown in FIG. For this reason, pressure fluctuations in the pipeline system and surging do not pose a problem.

Thus, according to the control method of the present invention,
High efficiency operation is performed by adjusting both the guide vane opening and the rotation speed in response to the AFC operation request, and only the rotation speed is adjusted in response to the high speed AFC operation request. Therefore, it becomes possible to drive with quick response.

(Other Embodiments) In the embodiment of the present invention shown in FIG. 1, the generator output Pg was not fed back, but Pg was fed back in order to accurately match the generator output Pg with the target value P ^* . An example is shown in FIG.

Reference numerals 1 to 9 are the same as those in FIG. 1, but unlike the case of FIG. 1, the difference ΔP ^* between the target output P ^* and the generator output Pg is applied to the filter circuit 10 having the same characteristics as the filter circuit 5. Is entered. Here, ΔP ^* is divided into a low speed operation command ΔPs and a high speed operation command ΔPf. ΔPs is input to the opening difference setting device 11 and converted into an opening difference signal Δa. The opening degree setting device 6 is the first
It has the same function as the embodiment in the figure, and has a head H and a low-speed operation signal.
The required opening a ^* is calculated from Ps. At that time, Δa is also taken into consideration when calculating a ^* .

According to the above configuration, ΔP ^* for a low speed operation command
And ΔPs match, the high-speed operation command ΔPf becomes zero,
The output change of the water turbine is performed only by the change of the guide vane opening. On the other hand, since ΔPs is zero, the rotation speed changes only through the high-efficiency operation commander 9, and therefore the rotation speed changes only slightly.

On the other hand, in response to a high-speed operation command, the rotation speed of the water turbine is changed by the high-speed operation command ΔPf, and control is performed so that Pg = P ^* . By the action of the filter circuit 5 and the filter circuit 10,
Since Ps and ΔPs hardly change, the guide vane opening a also hardly changes.

[Effects of the Invention] As described above, according to the present invention, even during high-speed AFC operation, the guide vane opening degree and the rotation speed are adjusted with respect to the given head and target output so that the turbine efficiency is maximized. Thus, an operation control method capable of highly efficient operation controlled by the above is realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a graph for explaining the operation thereof, and FIG. 3 shows the operation of the embodiment of the present invention shown in FIG. 4 and 5 are graphs for explaining the response when the target generator output P ^* changes slowly and when the target generator output P ^* changes abruptly in the above embodiment, and FIG. 6 shows the present invention. FIG. 7 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. 7 is a block diagram illustrating AFC operation of a conventional constant rotation speed operation water turbine,
8 and 9 are graphs showing a conventional operation control method for a variable speed water turbine. 1 ... Generator, 2 ... Turbine runner, 3 ... Guide vane, 4 ... Variable speed device, 5 ... Filter circuit, 6 ... Opening setting device, 7 ... Guide vane controller, 8 ... High-speed operation command device, 9 ... High-efficiency operation command device, 10 ... Filter circuit, 11 ... Opening difference setting device.

Claims (3)

[Claims] 1. A variable speed operation hydroelectric power generation system comprising a water turbine, a variable speed generator connected to the water turbine and capable of setting its rotation speed to an arbitrary value within a predetermined range, and a control device therefor. , The target generator output P ^* , or this P
^* Divided into the low speed component and high speed component of the difference between the actual generator output Pg [Delta] P ^* in the filter circuit and to control the water wheel guide vanes by the low speed component, controls the rotation speed of the variable speed generator with the high speed component A method for controlling a variable-speed operation hydroelectric power generation facility characterized by the above. 2. A target generator output P ^* is divided into a low speed component Ps and a high speed component Pf by a filter circuit, and the required guide vane opening a ^* is calculated from the low speed component Ps and the running head of the turbine at that time. The guide vane of the water turbine is controlled based on a ^* , and the rotation speed of the variable speed generator is controlled by the high speed component Pf so that this Pf becomes zero. Control method for variable speed hydropower plant. 3. A target generator output P ^* and an actual generator output Pg
And the difference ΔP ^* is calculated, and this ΔP ^* is divided into a low speed component ΔPs and a high speed component ΔPf by a filter circuit.
The rotation speed of the variable speed generator is controlled so that Pf becomes zero, and at the same time, the running head H of the water turbine and the target generator output P
2. The required guide vane opening a ^* of the water turbine is calculated based on the three factors ^* and the low speed component ΔPs, and the guide vane opening of the water turbine is controlled based on this a ^*. A method for controlling a variable speed operation hydroelectric power generation facility as described.