JPH05118268A - Automatically changing over device for number of nozzle of pelton wheel - Google Patents

Abstract

PURPOSE:To remove a fault that, in a Pelton wheel with plural number of nozzles whose operating number is automatically changed over to highly effective operating number according to the output of a hydraulic turbine, the total opening of a needle valve is overshot or undershot by the regulating error of a needle valve positioning switch or the unevenness of the end time of changing over to cause fluctuation in the output of the hydraulic turbine. CONSTITUTION:During changing over process executed by a nozzle changing over command, a signal 21 for nozzle being in changing over process is sent out to turn off the contact 13b of an opening command value changing section and to turn on the contact 13a, and the opening command value sent from the contact 13a is given to an opening adjusting section 6 to control a nozzle opening instead of an opening command value 12 on the side of a governor. On the other hand, a target opening computing section 14 computes the target opening after changing over the nozzles on a needle opening command value 22 at the time of receiving a changing over command, nozzle increasing and decreasing commands 23, 24, and the present number of operating nozzles. An automatic follow-up circuit 16c receives the computed target opening to send out the opening command value following from present opening toward the target opening to the contact 13a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically switching the number of operating nozzles in accordance with the output of a Pelton turbine having a plurality of nozzles to maintain high efficiency operation. In the following figures, the same reference numerals indicate the same or corresponding parts.

[0002]

2. Description of the Related Art Usually, a Pelton turbine has a plurality of nozzles, which may be of a 4-shot type or a 6-shot type. Since the efficiency of a Pelton turbine with a large number of nozzles is reduced when jets are ejected from all nozzles at partial load, the turbine efficiency is improved by operating by reducing the number of nozzles at partial load. Further, the output of the Pelton turbine is adjusted by controlling the opening of a needle valve provided in the nozzle portion. In the case of the 2 group control method of switching between 2 and 4 shots, the operation is performed with 2 nozzles until the turbine output is about 1/2, and the remaining when the needle valve opening during operation exceeds the maximum opening setting. Put 2 nozzles into the operation and operate with 4 nozzles. On the contrary, when the output is reduced, four nozzles are operated until the turbine output is about 1/2, and two nozzles are stopped when the needle valve opening during operation falls below the intermediate opening setting. Then, operate with the remaining two nozzles. In addition, the opening of the needle valve during operation is set to be the same as each other to make jet injection uniform.

In this operation of switching the nozzles,
For example, when increasing the number of nozzles from 2 to 4 shots, the preceding needle valve opening is closed from the maximum opening to a specified opening (opening ≅1 / 2 where there is no change in turbine output before and after the increase in the number of nozzles), In addition, it is necessary to reduce the output fluctuation due to the switching operation of the number of nozzles by conversely opening the subsequent needle valve opening to the specified opening. Conventionally, each needle valve is provided with a limit switch for opening the number of nozzles to start switching and a limit switch for the target opening after switching the number of nozzles for increasing and decreasing the number of nozzles, respectively, and performing sequential control.

[0004]

FIG. 4 shows a typical block diagram of a governor for controlling a four shot Pelton. However, the method of adjusting the deflector opening is not relevant to the present invention, and is therefore omitted from the configuration diagram. In the figure, 2 is a frequency setter, 1
Is a frequency detector, and 9 is a drooping rate calculator that gives the drooping characteristic of the water wheel speed to the nozzle opening for parallel operation of the generators. 3 is a speed deviation (that is, the difference between the output value of the frequency setting device 2 and the output value of the frequency detector 1) and the drooping rate calculating section 9
Of the needle valve opening command corresponding to the amount of water flowing into the Pelton turbine. The PID calculator 4 outputs the needle valve opening command value so that the input value becomes 0. A load limit setter for outputting a value, 5 is a PID calculator 3
Of the output opening command value of the load limit setting device 4 or the output opening command value of the load limit setter 4 is selected to be the opening command value 1 of the needle valve.
2 is the low value selection unit, NVR is NO. 1 to NO. 4 is a needle valve opening adjustment unit provided for each needle valve, 7 is an opening detector also provided for each needle valve, and 7a is a needle valve opening as an output of the opening detector 7. It is a detected value.

In the needle valve opening adjusting section NVR (however, in this example, only the NO.1 needle valve opening adjusting section is shown as a representative), 10 is a predetermined position of the needle valve of a predetermined nozzle. The corresponding NO. Output by the operation of the limit switch (not shown) to be detected. No. 1 to operate one nozzle. With the one-nozzle operation command, in this case, the above-mentioned opening command 12 is given to the opening adjustment unit 6 described below by a contact. No. 11 is the NO. No. 1 to stop 1 nozzle. With a 1-nozzle stop command, in this case, a 0 value is given to the opening adjustment unit 6 by a contact. Here, the opening adjustment unit 6 inputs the difference between the needle valve opening command value given by the operation command 10 or the stop command 11 and the needle valve opening detection value 7a, and sets the difference to 0. The valve control signal is set to NO. It has a role to output to the drive means (motor etc.) of the 1-needle valve. Next, 8 is the opening of all needle valves (that is, the detected value 7 of the needle valve opening of NO.1 to NO.4).
In the load setter that sets the sum of a), the deviation between the set value of the load setter 8 and the detected opening values of all needle valves is input to the droop rate calculation unit 9.

By the way, in a run-in power plant or the like to which the present invention is applied, power is generated according to the amount of flowing water in a river. Therefore, the speed control (governor control) loop using the PID calculator 3 is used when an accident is interrupted (that is, when an accident occurs). It is only used to prevent an excessive increase in speed when the turbine generator is disconnected from the grid), and is normally used only for the load limit setter 4
The control is performed according to the needle valve opening command value output by. Conventionally, therefore, the set value of the load setter 8 is set to the upper limit so that the needle valve opening command value output by the PID calculator 3 is less than the needle valve opening command value output by the load limit setter 4. By increasing the value, the needle valve is controlled by the "load limiting method" in which the value of the load limit setter 4 is selected and used as the opening setting value 12 for each needle valve. Further, the opening adjustment of each needle valve is performed by the opening adjustment unit 6 of each needle valve, and when the nozzle operation command 10 is closed, the needle valve opening command value 12 and the needle valve opening detection value 7a match. When the nozzle stop command 11 is closed, the opening command value is set to "0".
As a result, the needle valve is fully closed.

Here, as an example, the operation of switching from the 2-shot operation to the 4-shot operation will be described. When the setting of the load limit setter 4 is increased to 100% by a command from an external load adjusting device (not shown) in the 2-shot operation state, the needle valves of the two nozzles in operation open following this. , When the needle valve opening is opened to the position where the number of nozzles should be increased (that is, the position corresponding to 100% opening in this case), the limit switch that detects this opening position of the needle valve operates and Give a driving command. At this time, the load limit setter 4 simultaneously locks the signal input for external load adjustment (that is, cuts off the external signal for load adjustment until the switching of the number of nozzles is completed), and the preceding 2
The set position is lowered until the limit switches set to the switching end position (that is, the 50% opening position in this case) of the number of needle valves of that number are operated. At this stage, the subsequent two needle valves rapidly try to follow the opening position indicated by the load limit setter 4. In this way, the leading and trailing needle valves both try to move following the position of the load limit setter 4, but for control performance the full stroke time of the needle valve is 2 times the full stroke time of the load limit setter 4. ~
Since the speed is four times faster, in this case, the leading needle valve moves substantially following the load limit setter 4, but the trailing needle valve precedes the operation and the load limit setter 4 opens 50% from the 100% opening position. Before the set position is lowered to the degree position, the load limit setter 4 catches up with the opening position at that time. As a result, the total opening of each needle valve overshoots, causing fluctuations in the turbine output.

On the contrary, the operation when switching from the 4-shot operation to the 2-shot operation is performed by giving a stop command to two nozzles and
Although the position of the load limit setting device 4 is raised, the needle valve that is stopped also operates in advance in this case, so the total opening of each needle valve undershoots, and in this case also the fluctuation of the turbine output occurs. In addition, since the setting of the switching end position is also done by the mechanical limit switch provided on each needle valve, the setting accuracy cannot be increased.Therefore, it is difficult to match the turbine output before and after switching the number of nozzles. Adjustment was necessary every time the setting of the switching opening was changed. Therefore, an object of the present invention is to provide an automatic nozzle number switching device for a Pelton turbine that can solve such a problem.

[0009]

In order to solve the above-mentioned problems, an automatic nozzle number switching device according to claim 1 is provided with a plurality of nozzles, each of which is provided for each nozzle, and the needle valve of each nozzle is opened. Degree command value and opening degree detection value (7a, etc.) so as to match the needle valve control means (opening degree control section 6, etc.) that gives a control signal to the driving means (motor, etc.) of the needle valve of the nozzle concerned, power generation A first opening command value (12 or the like) is given to the needle valve control means of the number of operating nozzles selected so as to increase the turbine efficiency according to the output to be output,
In a Pelton turbine equipped with a means (load limit setting device 4 etc.) for giving an opening command value of 0 to the needle valve control means of the remaining stop nozzles, the nozzle currently in operation at the start of switching the number of nozzles to be operated. The number of nozzles (25, etc.), the command for increasing the number of nozzles (23, etc.) or the command for decreasing the number of nozzles (24, etc.), and the first of the needle valves for the nozzles currently in operation
Means for calculating the second opening command value of the needle valve for the nozzle to be operated after switching the number of nozzles based on the opening command value (22 as 12, etc.) or the detected opening value (target opening calculation part) 14) and the like, instead of the first opening command value or the opening command value of 0 to the needle valve control means of the nozzle to be operated after this switching during the switching operation of the number of operating nozzles. Means for giving an opening command value and giving an opening command value of 0 instead of the first opening command value to the needle valve control means of the nozzle to be newly stopped after this switching (opening command value switching Part 13, target opening selection part 15, etc.
(Hereinafter referred to as switching period opening command value output means)), and

According to a second aspect of the present invention, there is provided an automatic nozzle number switching device according to the first aspect, wherein the switching period opening command value output means gives the second needle valve control means to the second needle valve control means. An opening command value or a new opening command value of 0 is converted into a third opening command value and given to the needle valve control device. Correspondingly, the set opening automatic follow-up means gives the third opening command value to the needle valve control means at the switching start time, starting from the switching start time of the number of operating nozzles. Based on the first opening command value or the detected opening value that is set, the switching period opening command value output means tries to give the needle valve control means the second opening command value or a new zero value. To reach the opening command value, In follow-up possible rate of the dollar, and it shall be so varied with a same switching fairly time taken coordination of the nozzle comrades.

[0011]

In the present invention, the following means are provided. a) Means for storing the needle valve opening command value at the time when the nozzle number switching command is received, b) Nozzle number increase / decrease command, and nozzle switching mode from the currently operating nozzle number (2-shot to 4-shot operation, etc.) )
And switching the specific table in which the target opening is set after switching the number of nozzles, and referring to this specific table from the needle opening command value before switching stored by the storage means in a) above, after switching the number of nozzles Means for calculating a target opening, c) automatic follow-up means for controlling the opening / closing speed of the nozzle so that the speed at which the opening command value changes is the time during which each needle valve can respond. Thus, the target opening after switching the number of nozzles is automatically calculated by means of the above a) and b), and this value is used as the opening set value of each needle valve to determine the turbine output before and after switching the number of nozzles. It can be constant. Further, the limit switch that is set in the needle valve by automatically calculating the target opening can be only the one that detects the nozzle number switching start position, and therefore the position adjustment becomes easy.

The definition of the target opening set here is as follows:
Depending on the external load adjuster combined,
When the characteristics of the target opening degree calculation unit are set in advance, the mechanical characteristics that meet the requirements may be selected and set. For example, there are the following setting methods. 1) When the total needle valve opening during the nozzle switching operation is constant: the mechanical characteristics are linear (that is, 2 shots 1
00% = 4 shots 50%). 2) When the turbine flow rate during nozzle switching operation is constant: Refer to the needle valve opening / turbine flow rate characteristics using the head as a parameter to match the turbine flow rate before switching the number of nozzles with the turbine flow rate after switching. Set to. 3) When the generator output is constant during nozzle switching operation: Referring to the needle valve opening / generator output characteristic with the head as a parameter, the generator output before switching the number of nozzles and the generator output after switching To match.

Further, by providing the above-mentioned means c), the opening / closing speed of each needle valve becomes a speed set by the device regardless of the characteristic of the needle valve. Therefore, in the process of switching the number of needles, the needle valve which opens, It is possible to match the time required to reach the target opening degree of the closing needle valve, and as a result, it is possible to minimize the fluctuation of the turbine output during the switching process. Further, by providing this automatic follow-up means, it is possible to apply even a combination having a slight difference in the opening / closing speed peculiar to the needle valve.

[0014]

Embodiments of the present invention will be described below mainly with reference to FIGS. FIG. 1 is a configuration diagram of a main part of an automatic nozzle number switching device as a first embodiment of the present invention. This diagram is incorporated into each of four needle valve opening adjustment units NVR in the governor configuration diagram of FIG. FIG. 1 shows the control circuit of one (NO. 1 in this case) needle valve as a representative. The reference numerals are also used in FIG. 4 to clarify the connecting portion with FIG. This automatic nozzle number switching device is mainly composed of an opening command value switching unit 13 and a target opening calculation unit 1.
4, a target opening selection unit 15 and a set opening automatic tracking unit 16. The embodiment of FIG. 1 is an example in which the control loop for switching the number of nozzles and the control loop of the governor are completely separated, and the performance unique to the governor is not impaired when the generator frequency fluctuates during accident interruption. The device is configured to function only when the number of nozzles is switched.

The operation of FIG. 1 is as follows. a) When the nozzle switching signal output by the needle valve position detection limit switch or the like is received, the opening command value switching unit 13 turns off the setting 13b by the nozzle switching signal 21 that operates until the nozzle switching is completed, The contact point 13a is turned on to switch the needle valve opening command value given to the opening adjustment unit 6 from the governor side to the signal on the nozzle number automatic switching device side.

B) In the target opening calculation unit 14, the needle valve opening command value 12 (hereinafter referred to as 22 for distinction), the nozzle increase command 23 or the nozzle decrease command 2 when the nozzle switching command is received.
4, based on the current number of operating nozzles 25, etc.,
Next, the target opening of the needle valve of the nozzle to be operated next is calculated. Here, the nozzle increase / decrease commands 23 and 24 are also given by a needle valve position detection limit switch or the like. Further, in this case, the number of currently operated nozzles 25 and the nozzle increase command 23 or the nozzle decrease command 24 determine the nozzle to be operated next (and thus the number of operated nozzles). Further, the needle valve opening command value 22 at the time of receiving the nozzle switching command input by the target opening calculation unit 14 may be the needle valve opening detection value 7a at the same point instead.

C) With respect to the needle valve for which the operation command is issued, the target opening selection unit 15 (in other words, if the NO. 1 nozzle operation command 10 is valid in this case), the target opening calculation unit 14 Selectively output the target opening calculation value output by
For the needle valve for which a stop command has been issued (in other words, if the No. 1 nozzle stop command 11 is valid)
Select and output the command value of "0".

D) In the next set opening automatic follow-up unit 16, the contact point 16a is turned on by the above-mentioned nozzle switching signal 21.
16b is turned off, and the automatic follow-up circuit 16c automatically follows the command value selected by the target opening degree selection unit 15 in the preceding stage to the output opening valve set value.
This output value is output to the opening adjustment unit 6 side as the actual opening command value 16d of the needle valve. Then, in this case, the output opening command value 16d of the automatic follow-up circuit 16c of each needle valve involved in switching from the time of outputting the nozzle switching signal becomes equal to the opening command value output by the target opening selecting unit 15 at the preceding stage. Until the time (following time) is equal to each other,
Moreover, the changing speed of the output opening command value 16d is set in advance so as to be as high as possible for the nozzle to follow.

Note that the lower contact 16b in the set opening automatic follower 16 is closed during normal operation when the nozzle switching signal 21 is not output, and the input to the automatic follower circuit 16c is input from the needle valve opening detector 7. By setting the needle valve opening detection value 7a to be output, the output of the automatic follow-up circuit 16c is always set as the current actual needle valve opening, and when nozzle switching is in progress, the switching operation is transitioned without shock. Have a role.

E) Coordination of the time required for each needle valve to reach the final target opening by the opening adjuster 6 changing at a speed at which each needle valve given from the set opening automatic follower 16 can respond. Stable control is performed according to the opening command value that has been taken, and when the final target opening is reached, the nozzle number switching operation ends.

FIG. 2 is a block diagram of a nozzle number switching device according to a second embodiment of the present invention. In the embodiment of FIG. 2, among the functions of the control loop when switching the number of nozzles of FIG.
In this example, the target opening degree selection unit 15 is shared with that of the governor control loop, and the set opening degree automatic follow-up unit 16 is incorporated into the governor control loop to simplify the circuit. In the circuit of FIG. 2, the opening command value given to each needle valve always passes through the automatic tracking circuit 16c described in the set opening automatic tracking unit 16 of FIG. Compared with the circuit of No. 1, there may be a slight delay in the governor's original performance when the generator frequency fluctuates during accident shutdown. However, the full stroke time of a needle valve is usually as long as several tens of seconds, while the delay time is at most 1 to 2 seconds, which is not a practical problem. In particular, when a large frequency fluctuation such as when the load is cut off is applied to a governor forming a frequency control loop by a deflector independent of the control loop of the needle valve, there is no problem.

Next, FIG. 3 is a block diagram of an automatic nozzle number switching device as a third embodiment of the present invention, in which the set opening automatic follower 16 is omitted from FIG. In this case, the time required for each needle valve to reach the final target opening is not coordinated, but the target opening calculation unit 14 instructs the opening adjustment unit 6 to set the correct needle valve target that should be present after switching the number of nozzles. Since the opening degree is given, it is possible to prevent the fluctuation of the turbine output based on the setting error of the switch position because the target nozzle opening degree has been fixedly given by the limit switch at the time of switching the number of nozzles.

[0023]

According to the first aspect of the present invention, a plurality of nozzles are provided for each nozzle so that the opening command value and the detected opening value 7a of the needle valve of the nozzle are matched. A needle valve control means (such as an opening adjustment part 6) for giving a control signal to a needle valve drive means (a motor or the like) of the nozzle concerned, and a number of operating nozzles selected so as to enhance the turbine efficiency in accordance with the output to be generated. Pelton equipped with a means (load limit setting device 4 etc.) for giving a first opening command value 12 to the needle valve control means of 1 and an opening command value of 0 to the needle valve control means of the remaining stop nozzles. In the water turbine, at the start of switching the number of operating nozzles, the number of currently operating nozzles is 25, the command 23 to increase or decrease the number of nozzles, and the first opening of the needle valve for the currently operating nozzle. A target opening calculation unit that calculates a second opening command value (target opening) of the needle valve for the nozzle to be operated after switching the number of nozzles based on the command value (as 12) 22 or the detected opening value 7a. 14 and the first opening command value 12 or 0 to the needle valve control means of the nozzle to be operated after the switching of the number of operating nozzles.
The second opening command value instead of the opening command value of
Further, means for giving an opening command value of 0 instead of the first opening command value to the needle valve control means of the nozzle to be newly stopped after this switching (opening command value switching unit 13, target opening selection Hereinafter referred to as a switching period opening command value output means), and

According to the invention of claim 2, claim 1
In the automatic number-of-nozzles switching device according to item 3, the switching period opening command father output means gives the second opening command value or a new zero opening command value to each of the needle valve control means. A set opening automatic follow-up unit 16 provided by converting into an opening command value is provided corresponding to each of the needle valve control means,
The set opening degree automatic follow-up means respectively sets the third opening degree command value to a starting point at which the switching of the number of operating nozzles is started.
The first opening command value 22 or the opening detection value 7 given to the needle valve control means at the time when the switching is started.
It is possible to follow the needle from a toward the second opening command value or the new opening command value of 0 which the switching period opening command value output means is trying to give to the needle valve control means. Since the speed is changed at the same switching time with the cooperation of the nozzles,

In the process of switching the number of nozzles, and before and after the process, it is possible to maintain a constant state according to the purpose of the water turbine, and the opening of the number of nozzles switching can be easily set without any other adjustment. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration as a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration as a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration as a third embodiment of the present invention.

FIG. 4 is a typical configuration diagram of a main part of a governor for controlling a four-shot Pelton turbine.

[Description of symbols] 1 frequency detector 2 frequency setter 3 PID calculator 4 load limit setter 5 low value selector 6 opening adjustment unit 7 needle valve opening detector 7a needle valve opening detected value 8 load setter 9 Droop rate calculation unit 10 Nozzle operation command 11 Nozzle stop command 12 Needle valve opening command value 13 Opening command value switching unit 14 Target opening calculation unit 15 Target opening selection unit 16 Set opening automatic tracking unit 16c Automatic tracking circuit NVR Needle valve opening adjustment unit 21 Nozzle switching signal 22 Needle valve opening command value when nozzle switching command is received 23 Nozzle increase command 24 Nozzle decrease command 25 Current number of operating nozzles

Claims (2)

[Claims] 1. A plurality of nozzles, each of which is provided for each nozzle, and to a driving means of the needle valve of the nozzle so that the opening command value and the detected opening value of the needle valve of the nozzle respectively match. Needle valve control means for giving a control signal, giving a first opening command value to the needle valve control means of the number of operating nozzles selected to increase the turbine efficiency according to the output to be generated, and the remaining stop nozzles In a Pelton turbine equipped with a means for giving an opening command value of 0 to the needle valve control means, at the start of switching the number of operating nozzles, the number of nozzles currently in operation, an instruction to increase or decrease the number of nozzles, and an actual operation The second opening command value of the needle valve for the nozzle to be operated after switching the number of nozzles based on the first opening command value or the detected opening value of the needle valve for the inner nozzle; Means for calculating power and, during the switching period of the number of operating nozzles, to the needle valve control means of the nozzle to be operated after this switching, instead of the first opening command value or the opening command value of 0, the second opening command value Means for giving an opening command value of 0 instead of the first opening command value to the needle valve control means of the nozzle to be newly stopped after this switching (hereinafter referred to as switching period opening Degree command value output means)), the automatic switching device for the number of nozzles of the Pelton turbine. 2. The automatic nozzle number switching device according to claim 1, wherein the switching period opening command value output means gives the second opening command value to the needle valve control means or a new zero value. A set opening automatic follow-up means is provided corresponding to each of the needle valve control means, the set opening automatic follow-up means being provided by converting the opening instruction value into a third opening command value. Starting from the switching start time of the third opening degree command value,
From the first opening command value or opening detection value given to the needle valve control means at the start of switching,
At the speed at which the needle can follow, toward the second opening command value or the new opening command value of 0, which the switching period opening command value output means tried to give to the needle valve control means. An automatic nozzle number switching device for a Pelton turbine, characterized in that the nozzles are changed at the same switching time in which the nozzles cooperate with each other.