JPS63178796A - Control device for variable-speed waterwheel generation system - Google Patents

Abstract

PURPOSE:To permit effectual operation at all times, by controlling the speed and the output of a variable-speed waterwheel generation system stably and quickly in compliance with the output requirement. CONSTITUTION:A guide vane controller 4 controls the opening of a guide vane so as to form the opening in compliance with the guide vans opening command from an output control system 5. An output response compensation section 8 outputs a guide vane opening criterion to set a criterion when the optimum speed is found in compliance with the guide vane opening command from the output control section 5. A function generation section 9 outputs the speed command based on the guide vane opening criterion from the output response compensation section 8 and the static head. A speed control section 6 outputs the output command to a variable frequency power source so as to get the speed in compliance with the speed command from this function generation section 9.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a water turbine or a pump-turbine equipped with a guide vane, a generator or a generator-motor directly connected to the water turbine or the pump-turbine, and a generator-motor connected directly to the water turbine or the pump-turbine. The speed and output of a variable speed water turbine power generation system consisting of a generator or a variable frequency power source that applies excitation power to a generator motor are determined by the opening degree of the guide vane and the
The present invention relates to an improvement of a control device that is controlled by excitation power of a generator or a generator motor.

(Prior art) The efficiency η of a water turbine is defined by the unit speed n (however, the unit speed is the speed N
is the speed normalized by the head, which is n-N/JH), and varies depending on the guide vane opening a, and is generally shown as shown in FIG. In other words, as is clear from Figure 4, conventional water turbines are operated with constant N, so in power plants with large head fluctuations, or power plants with a large operating output range and large guard vane opening changes, They are forced to drive inefficiently. For this reason, in order to achieve high efficiency operation regardless of head or output, variable speed water turbine power generation systems that change the speed of the water turbine according to head and output have begun to be considered (for example, "Unexamined Japanese Patent Publication No. No. 57-113971”).

FIG. 5 shows an example of this type of variable speed water turbine power generation system. In FIG. 5, in the secondary winding of an induction generator 2 directly connected to a water turbine 1 equipped with a guide vane IA,
By applying the output of the variable frequency power supply 3 as excitation power, the primary winding of the induction generator 2 is configured to generate power in synchronization with the grid. - the force control device has an output demand P;

an output control section 5 that generates an output command ER of the variable frequency power supply 3 from the output request P of "1. From the static head H8T,
A function generating section 7 that outputs a speed command NR that provides maximum efficiency, a speed control section 6 that outputs a guide vane opening command AR based on the speed command NR from this function generating section 7, and this speed control section 6. The guide vane control device 4 controls the guide vane opening A so that the opening corresponds to the guide vane opening command AR.

According to the above configuration, the guide vane opening degree A is the output request P
The excitation power E of the induction generator 2 is controlled to the output command ER of the variable frequency power supply 3 to realize the output request Po. This enables efficient operation.

However, a control device for a variable speed water turbine power generation system as described above has a disadvantage of poor transient characteristics. - As an example, static head HST, output P1. Speed N1.
Guide vane opening A1. From the first operating point, which is the excitation power E1, the static head HST.

Output P1+ΔP, speed N1+ΔN, guide vane opening A
The transient characteristics when changing to the second operating point which is 1+ΔA and excitation power E1+ΔE will be explained. Note that to simplify the explanation, it is assumed that the static head difference does not change.

That is, when the static head difference H8T is constant, the input/output characteristics of the function generator 7 are approximately NR= and Po.

Here, K1 is a positive constant determined by the static head difference. Therefore, the output demand P for changing from the first operating point to the second operating point. When ΔP is increased from Pl, the speed command NR
also increases by ΔN from N1, and the output command ER also increases by ΔE from El. As a result, guide vane opening A1 generator excitation power E
Both begin to increase. Also, the change d in the guide vane opening degree A
As is well known, the relationship between A and the change dPM in the water turbine output PM is expressed by a transfer function as shown in the following equation.

dA 1 1+-2-Tw ・S However, Tw is the channel constant determined by the channel cross-sectional area and channel length,
Usually it is about 0.6 to 2.0 seconds. On the other hand, since the delay in the generator output P from the change in the generator excitation power E is only a few milliseconds, the output demand P1 increases faster than the increase in the turbine output P)I, and the speed N conversely decreases. Put it away. Also, from the change dA in the guide vane opening A, the change dP in the water turbine output PM
Due to the delay up to M, the characteristics of the speed control section 6 are unstable and have poor responsiveness. Therefore, as shown in FIG. 6, the speed N settles slowly, and it takes time to reach the second operating point.

(Problems to be Solved by the Invention) As described above, in the conventional control device for a variable speed turbine power generation system, it is difficult to maintain stability when controlling the speed and output of the variable speed turbine power generation system in accordance with the output request. However, there was a problem in that the performance and responsiveness were poor, and the system could not be operated efficiently.

Therefore, the present invention has developed a highly reliable variable speed water turbine power generation system that can stably and quickly control the speed and output of the variable speed water turbine power generation system in accordance with output demands, and can always operate efficiently. The purpose of this invention is to provide a control device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a water turbine or a pump-turbine equipped with a guide vane, and a generator or a generator directly connected to the water turbine or the pump-turbine. The speed and output of a variable speed water turbine power generation system consisting of a generator motor and a variable frequency power supply that applies excitation power to the generator or generator motor are controlled by the opening degree of the guide vane and the opening of the generator or generator motor. In a control device that is controlled by excitation electric power, there is an output control section that outputs a guide vane opening command according to an output request, and a guide vane that outputs a guide vane opening command according to the guide vane opening command from the output control section. A guide vane control device that controls the opening degree, and a guide vane opening command from the output control section.

or an output response compensation unit that outputs a guide vane opening reference based on either the guide vane opening, and outputs a speed command based on the guide vane opening reference from this output response compensation unit and the static head difference. The present invention is characterized in that it includes a function generating section and a speed control section that outputs an output command to the variable frequency power source so that the speed corresponds to the speed command from the function generating section.

(Function) In the control device for the variable speed turbine power generation system described above,
Output control by guide vane opening control and speed control by excitation power control from a variable frequency power source are performed simultaneously, achieving control to obtain generator output at a speed with high efficiency of the water turbine in response to output requests. Furthermore, in response to a rapidly changing output request that cannot be followed by guide vane opening control, the generator output can be made to follow by temporarily changing the speed reference.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 1 shows a configuration example of a variable speed water turbine power generation system to which a control device according to the present invention is applied, and the same element names as in FIG. 5 are given the same reference numerals. In Figure 1,
A variable speed water turbine consisting of a water turbine 1 equipped with a guide vane IA, an induction generator 2 directly connected to the water turbine 1, and a variable frequency power supply 3 that applies excitation power to the secondary winding of the induction generator 2. The control device for controlling the speed and output of the water turbine power generation system consists of the following: That is, the guide vane opening command A according to the output request Po
an output control unit 5 that outputs R, a guide vane control device 4 that controls the guide vane opening A so that the opening corresponds to the guide vane opening command AR from the output control unit 5; Based on the guide vane opening command AR from section 5.

An output response compensator 8 outputs a guide vane opening reference AR, which is a reference when determining the optimum speed, a guide vane opening reference AR1 from this output response compensator 8, and a static head H.
A function generator 9 outputs a speed command NR based on 8T.
and a speed control section 6 that outputs an output command ER to the variable frequency power supply 3 so that the speed corresponds to the speed command NR from the function generation section 9.

Here, the output control unit 5 receives a generator output P detected by an output detector (not shown) and an output request P.

an adjuster 51 that detects the deviation between the
The speed control unit 6 is comprised of an adjuster 61 that detects the deviation ΔN between the speed N detected by a speed detector (not shown) and the speed command NR mentioned above, and a proportional controller 62. There is. Further, the function generator 9 determines the speed at which the efficiency is maximized given the guide vane opening degree and static head difference from the water turbine characteristics. Furthermore, the output response compensator 8 determines the guide vane opening reference to be input to the function generator 9 so as to improve the output response.
The detailed calculation method will be described later.

Next, the operation of the control device for the variable speed water turbine power generation system configured as described above will be described with reference to FIG. 2(a).

Note that FIG. 2(a) is a block diagram showing the operating characteristics of the entire control system in FIG. 1.

In FIG. 2(a), cp (S) is the characteristic of the proportional-integral controller 52 of the output control section 5, where Kp is the proportional gain and Tp is the integral time constant. Also, GT
(S) shows the response of the water turbine output PM to the guide vane opening command AR. If the delay time constant of the guide vane control device 4 is Tv and the waterway time constant is Tw, normally T
Since v(Tw), K1 is a value obtained by linearly approximating the guide vane opening versus speed characteristic of the function generator 9 near the operating point.T
is a water wheel 1. The inertia time constant of the induction generator 2, KN, indicates the proportional gain of the proportional controller 62 of the speed control section 6, and is KN)1.

On the other hand, Gc (S) indicates the characteristics of the output response compensator 8, but in order to clarify the role that Gc (S) plays in output control, equivalent transformation on the block is performed and the second
The result will be as shown in figure (b). As is clear from FIG. 2(b), it can be seen that the response of the output P to the guide vane opening command AR can be improved. In addition, Gc(
It goes without saying that the case where S)=O corresponds to the output control system of the conventional constant speed water turbine power generation system.

Next, how to determine Gc (S) will be explained.

Now, the desired response of the output P to the guide vane opening command AR is set as P=Gx (S)AR, and Gc (S)
), the response improvement is defined as Gc (S) and Gc (
S) is calculated as follows: =GT(S)-Gc'(S) ・Kl -T-8. - As an example, if Gx(S)-1, Tw,
2TIK11+ ・S ]−. By the way, in order to operate the water turbine 1 efficiently, it is desirable that Gc (S) be 1, so for a component faster than the output control system response of the guide vane opening command AR, Gc (S) #Gc'(S), and for a component slower than the output control system response of the guide vane opening command AR, set Gc(S) so that Gc(S)=1.
Once Gc (S) is determined, Gc (S) can be obtained as shown in the following equation.

As a result, the change from the first operating point shown above to the second operating point becomes as shown in FIG. 3. From FIG. 3, the same output request P. On the other hand, it can be seen that the stability of the speed N is improved and the initial response of the output P is also improved compared to FIG. 6 described above.

As described above, in the control device for the variable speed water turbine power generation system configured in this embodiment, output control by guide vane opening control and speed control by excitation power control from the variable frequency power source are performed simultaneously, and the output request is This system realizes control that obtains generator output at a speed that is highly efficient for the water turbine, and also temporarily changes the speed standard in response to a fast-changing output request that cannot be followed by guide vane opening control. This allows the generator output to be tracked.

As a result, when an attempt is made to increase (or decrease) the output, the output temporarily decreases (or increases). This phenomenon disappears. In addition, it quickly reaches a highly efficient operating point according to the output demand, that is, the speed and guide vane opening that are most efficient for generating that output with the static head at that time, resulting in extremely efficient power generation operation. This has the effect of making it possible to perform the following.

It should be noted that the present invention is not limited to the embodiments described above, but can also be implemented in the following manner.

(a) In the embodiment shown in FIG. 1 above, a case has been described in which the output response compensator 8 outputs the guide vane opening reference AR based on the guide vane opening command AR from the output controller 5. The present invention is not limited to this, and even if the output response compensator 8 outputs the guide vane opening reference AR1 based on the guide vane opening A, the same effect as described above can be obtained.

(b) In the above embodiment, the present invention is applied to a variable speed water turbine power generation system consisting of a water turbine and an induction generator directly connected to the water turbine, but the present invention is not limited to this. The present invention can be similarly applied to a variable speed water turbine power generation system composed of a generator motor.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, there is provided an output control unit that outputs a guide vane opening command in response to an output request, and an output control unit that outputs a guide vane opening command in response to an output request, and an output control unit that outputs a guide vane opening command in response to an output request, and a guide vane control device that controls the guide vane opening so that the guide vane opening is controlled, and a guide vane opening command from the output control section;
or an output response compensation unit that outputs a guide vane opening reference based on either the guide vane opening, and outputs a speed command based on the guide vane opening reference from this output response compensation unit and the static head difference. The variable speed water turbine power generation system is configured to include a function generation section and a speed control section that outputs an output command to the variable frequency power source so that the speed corresponds to the speed command from the function generation section. The speed and output of the machine can be controlled stably and quickly by following the output request,
It is possible to provide an extremely reliable control device for a variable speed water turbine power generation system that can always operate efficiently.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a variable speed water turbine power generation system to which a control device according to the present invention is applied, Fig. 2(a) is a block diagram showing the characteristics of the entire control system in the same embodiment, Fig. (b) is an equivalent block diagram of the response characteristics in FIG. 2(a), and FIG. 3 is a diagram showing the response characteristics in the same example.
FIG. 4 is a diagram showing characteristics of a water turbine, FIG. 5 is a block diagram showing an example of a conventional variable speed water turbine power generation system, and FIG. 6 is a diagram showing response characteristics in FIG. 5. DESCRIPTION OF SYMBOLS 1... Water turbine, IA... Guide vane, 2... Induction generator, 3... Variable frequency power supply, 4... Guide vane control device, 5... Output control part, 51... Adjuster,
52... Proportional-integral controller, 6... Speed control section, 61
...Adjuster, 62...Proportional controller, 7...Function generator, 8...Output response compensation unit, 9...Function generator, Po...Output request, P...・Output, AR...Guide vane opening command, A...Guide vane opening, H3T
...Static head difference, NR...Speed command, N...Speed, E
R: Variable frequency power supply output command, E: Excitation power of induction generator 2, PM: Water turbine output.

Claims (1)

[Claims] A variable speed water turbine consisting of a water turbine or pump water turbine equipped with guide vanes, a generator or generator motor directly connected to the water turbine or pump water turbine, and a variable frequency power supply that applies excitation power to the generator or generator motor. In a control device that controls the speed and output of a power generation system by the opening degree of the guide vane and the excitation power of the generator or generator motor, an output control section outputs a guide vane opening degree command according to an output request; , a guide vane control device that controls the guide vane opening so that the opening corresponds to the guide vane opening command from the output control unit; and a guide vane opening command from the output control unit or the guide vane opening. an output response compensator that outputs a guide vane opening reference based on either the output response compensator, and a function generator that outputs a speed command based on the guide vane opening reference from the output response compensator and the static head difference. and a speed control section that outputs an output command to the variable frequency power source so that the speed corresponds to the speed command from the function generation section. Control device.