JP2846785B2 - Deflector damage detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflector breakage detecting device in a hydroelectric power plant having a Pelton turbine.

[0002]

2. Description of the Related Art FIG. 9 shows a schematic structure of a Pelton turbine.
In the figure, a water pipe 31 for guiding water from a head tank (not shown) is provided with branch pipes 32 and 32a branched into a plurality. A needle shaft 33a having a needle 33 at the distal end of each of the branch pipes 32, 32a penetrates the curved pipes 34, 34a, respectively.
5, 35a are supported by bearings (not shown) provided and reciprocated by a driving device (not shown). By reciprocating the needle shaft 33a, the needle 33 is inserted into and pulled out of the nozzles 36, 36a, so that the opening of the nozzle is adjusted, and the water flow from the head tank is jetted at this opening as a jet water flow. This jet water stream hits a number of buckets 37a provided on the runner 37, and rotates the runner 37 in the direction of the arrow. And runner 37
A generator connected to the shaft 37b is driven to extract electric power.

[0003] The deflectors 38 and 38a are rotatably provided so as to cover the nozzles. During normal operation, the positions of the needle and the deflector are in an optimum relationship due to the correlation characteristics between the needle and the deflector. The deflector always directs the jet to the turbine, and when it becomes necessary to deflect the jet (with respect to the turbine), the deflector stands by at a position where the operation can be performed without wasting time.
The deflector covers the nozzle so as to change the direction of the jet water jet spouted from the nozzle when the system is shut off, thereby preventing an abnormal increase in the rotational speed of the runner and a sudden increase in the pressure of the penstock.

Numerals 1 and 4 denote servo motors for the needle and the deflector. Numerals 12 and 10 conceptually show a mechanical connection between the needle servo motor and the needle and a deflector servo motor and the deflector, respectively. Further, reference numerals 2 and 6 are opening degree detectors which detect the opening degree of the needle and the deflector in conjunction with the servomotor, and detect signals such as a needle fully closing signal (74NL) and a deflector fully closing signal (74DL) here. Is done.

Next, the deflector discharge of the Pelton turbine will be described. In a normal power plant, when shutting down a water turbine / generator at the time of inspection or an accident, etc., water is supplied by completely closing an inlet valve provided on the upstream side of the water guide pipe 31 shown in FIG. I try to shut it off. As a result, the water used for power generation is left over, and is usually overflowed through a spillway provided in the upper water tank. By the way, in order to reduce the cost of civil engineering construction, in a spillway-omitted power plant where such a spillway is omitted, all the water taken from a distant intake gate must be discharged from a nozzle. Water fills the waterway tunnel provided between the water tank and the water pressure, which has an undesirable effect on the waterway tunnel. For this reason, in a spillway-free power plant, it is necessary to completely close the deflector to completely deflect the water flow from the nozzle and to discharge excess water so as not to hit the bucket of the runner to prevent the water level in the upper water tank from rising. Also, during such deflector discharge, the bounced water hits the runner and may be a weak but driving force, so even in this case, the brake is applied so that the water turbine and generator do not rotate. .

FIG. 10 shows the relationship among a power system, a generator and a speed relay. The driving force given to the water turbine WT is converted into electric power by the generator G and supplied to the high-voltage power system through the circuit breaker 52 and the main transformer. When an accident occurs in the generator G or the system, the circuit breaker 52 is quickly opened to prevent the accident from spreading. The speed of the turbine / generator is controlled by a mechanically connected speed signal transmitter (SS
G: Speed Signal Generator)
The speed relays 12, 13, 141 and 142 are respectively operated by this electric signal, and a speed signal is obtained.

[0007]

By the way, conventionally, it is difficult to directly detect the damage of the deflector.
When the water jet from the nozzle is cut off or discharged by the deflector during the stop process, the deflector is damaged, and as a result, the rotation speed of the turbine / generator increases to the operating speed of the overspeed relay (see reference numeral 12 in FIG. 10). However, this relay operates indirectly as a result of operation. This overspeed relay is installed mainly for the purpose of detecting the abnormal increase in the rotation speed due to the abnormality of the governor of the turbine / generator and protecting the turbine / generator. The maximum speed fluctuation rate at the time is set with a margin of about 5%.

As described above, since the deflector breakage can be detected only in the overspeed region, the following problems occur. (1) Since the detection is only performed by the overspeed relay, it is not possible to identify the cause of the abnormality due to an abnormality in the governing system or the deflector being damaged. (2) Since the detection is performed after the overspeed, the rotation speed of the turbine / generator always reaches the unconstrained speed, which adversely affects the turbine / generator. (3) When the deflector is discharged, the brake is normally applied and the deflector deflects the water jet from the nozzle to discharge it. Therefore, in the detection of only the overspeed region, the deflected water jet hits the runner of the turbine and the rotational torque. This causes the water turbine to rotate while the brake is applied, leading to a situation such as burning of the brake or occurrence of a fire. Therefore, an object of the present invention is to detect a deflector breakage quickly and reliably.

[0009]

According to the present invention, in order to solve such a problem, in a hydroelectric power plant having a Pelton turbine, when the turbine / generator is stopped or when the deflector is discharged, the water flow from the nozzle is deflected by the deflector. Detecting that a part or all of the jet is shut off, holding means for holding the result, and monitoring the rotation speed of the water turbine / generator in the state, and detecting that an overspeed condition has occurred. In the same manner as the first detecting means for detecting, while the water jet is shut off, the rotation speed of the turbine / generator is monitored, and after the rotation speed once decreases to the specified speed, the rotation speed exceeds the specified speed again. A second detecting means for detecting that the number has risen, and also monitoring the rotation speed of the water turbine / generator while the water jet is shut off,
A third detecting means for detecting that the rotation speed has once again increased to or higher than the braking operation speed even though the rotation speed has once decreased to the braking operation speed, and the water jet has been cut off; Monitoring the number of rotations of the turbine / generator and detecting that the number of rotations has once decreased to the braking operation speed, the brakes have been operated, and the turbine / generator has stopped completely and has started to rotate again. 4
Detecting means for monitoring the number of rotations of the turbine / generator while the water jet is shut off, and detecting that the number of rotations does not decrease to the specified speed within a time that is predicted in advance. And detecting means for outputting a deflector damage signal to the outside in response to any of the outputs from the detecting means, and outputting a brake release signal when the brake is in operation.

[0010]

[Function] The deflector is normally operated with an opening that does not cut off the water jet from the nozzle. However, in the event of an accident, the deflector controls the water jet from the nozzle to the runner to suppress the increase in the rotation speed of the turbine / generator. It is controlled to be deflected from the direction. At this time, since the turbine / generator normally moves in the stop direction, the rotation speed gradually decreases, but when the deflector is damaged, it operates as shown in FIG. 4 to FIG.

(1) If the deflector breaks during normal operation, after the load is cut off due to the occurrence of an accident, the rotational speed rises above the normal maximum speed fluctuation rate, and even if the deflector is fully closed, the damaged deflector may be damaged. The rotational torque is given by the water jet from the corresponding nozzle, so that the rotational speed does not decrease. That is, this corresponds to the case of FIG. 4, but this case is detected by the first detection means. When the needle opening is small and the rotation torque is small, the increase in the rotation speed is not so large even after the load is cut off due to an accident, and the rotation cannot be detected by the first detection means (see FIG. 8).
Therefore, this state is detected by the fifth detecting means.

(2) If the deflector is damaged during the stopping process, the rotational speed once decreased again increases,
The operation patterns are as shown in FIG. 5, FIG. 6, and FIG. 7A, and these are detected by the second, third, and fourth detection means, respectively. (3) When discharging the deflector, the deflector is fully closed and the water turbine / generator is braked to discharge water from the nozzle. If the deflector is damaged at this time, the rotational torque of the water jet is higher than the braking torque by the brake. , The turbine / generator starts to rotate. FIG. 7B shows the transition at this time, and this is detected by the fourth detection means.

[0013]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a circuit diagram showing a specific example of a circuit for judging a water jet cutoff state, FIG. 3 is a circuit diagram showing an abnormal signal and a brake release command output circuit, and FIGS. 4 to 8 are diagrams for explaining operation patterns of a water turbine / generator. FIG. First, FIG. 2 will be described. In the figure, AND10 to AND12 indicate AND gates, OR1 indicates an OR gate, NOT7 to 9 indicate NOT gates, and FF4 indicates a flip-flop. 1X is an operation command, and 4X is a start command. Here, when the operation command 1X is received, the operation command is given to the auxiliary motors to secure the hydraulic oil and the cooling water necessary for the actual operation, and when the hydraulic pressure and the cooling water flow are established, the 4X operates. ,
This is a start command for the turbine / generator.

In the process of stopping the turbine / generator or the deflector during the discharge of the deflector, the state of the water jet cutoff is as follows.
Under the condition that X and 4X have returned, the circuit breaker for power generation (52: see FIG. 10) opens and the deflector is fully closed (74).
DL) and the needle or inlet valve is fully closed (74N
L). This result is held by the flip-flop FF4 and output as the signal M1. To release the flip-flop FF1, both the deflector and the needle (or the inlet valve) are fully closed (74NL)
And the water flow jet cutoff state disappears (when the output of the AND gate AND12 is obtained via the OR gate OR1), or when a start command of the turbine / generator is received and the operation shifts to the operation (AND gate AND1)
0 is obtained via the OR gate OR1).

Referring to FIG. As shown in the drawing, this circuit receives a signal M1 and detects detection signals S1 to S5.
Is output from five detecting means. In other words, if the deflector breaks during normal operation, after the load is cut off due to the occurrence of an accident, the rotation speed rises above the normal maximum speed fluctuation rate, and even if the deflector is fully closed, the rotation from the nozzle corresponding to the damaged deflector Since the rotational torque is given by the water jet, the rotational speed does not decrease. That is, when the rotation speed of the turbine / generator changes as shown in FIG.
1 and outputs a signal S1. This signal S1
Specifically, the signal M1 from the determination circuit of FIG.
It is obtained by an AND condition with a signal N12 indicating that the rotation speed of the generator has exceeded the operation level of the overspeed relay 12 in FIG. 10 (overspeed state).

The second detecting means corresponds to the operation pattern shown in FIG. 5, and when M1 is being output, the specified speed N1 which is the operation level of the relay 13 shown in FIG.
3 is detected via a NOT gate NOT1, an AND gate AND2, and a timer T1, and this state is stored to output a signal M2.
F1 and an AND gate AND3 that outputs a signal S2 in response to a signal N13 indicating that the number of revolutions has exceeded the specified speed again after the state M2 has been reached. The timer T1 is used for preventing malfunction or checking the state, and the release of the flip-flop FF1 is controlled by the signal M.
This is performed by eliminating 1, but this point is not directly related to the basic operation.

The third detecting means corresponds to the operation pattern shown in FIG. 6. In the state where M2 is being output, the deflector is fully closed (74DL), and the number of revolutions further decreases, so that the relay 141 shown in FIG. The operation level is lower than the brake operation speed N141 and the operation of the brake (75Z) is detected via the AND gate AND5 and the timer T2, and this state is stored, and the flip-flop FF2 which outputs the signal M3, And an AND gate AND6 that outputs a signal S3 when the rotation speed increases again and the signal N141 that is lower than the brake operation speed disappears, on condition that the brake operation speed is once lower than the brake operation speed N141 (state of M3). ing. The operation of the flip-flop FF2, the operation of the timer T2, and the like are the same as those of the second detection unit.

The fourth detecting means corresponds to the operation patterns shown in FIGS. 7A and 7B. When M2 is output, the deflector is fully closed (74DL), and the brake is operated (75Z). ) And the relay 1 shown in FIG.
A flip-flop FF3 that operates via the AND gate AND7 and the timer T3 on condition that the turbine / generator is stopped at 42 (signal N142), stores this state and outputs a signal M4, And the stop signal N14 on the condition that the stop signal is temporarily stopped (the state of M4).
2 and an AND gate AND8 that outputs a signal S4 when a new rotation occurs. The release of the flip-flop FF3 and the operation of the timer T3 are the same as those of the second detecting means.

The fifth detecting means corresponds to the operation pattern shown in FIG. 8, and when M1 is output, the number of revolutions of the turbine / generator is set to a predetermined time (normal And a gate S9 that detects that the speed does not drop below the prescribed speed N13 and outputs a signal S5 within a predetermined time.

By inputting the deflector damage signals S1 to S5 obtained as described above to the OR gate OR2 in FIG. 3 and introducing them to the flip-flop FF5 via the timer T5, at least one of the signals S1 to S5 becomes significant. Then, the flip-flop FF5 is set and the signal F1 can be obtained. Here, the signal F1 is output as an abnormal signal indicating that the deflector has been damaged, and is also used as a command for releasing the brake during a braking operation. The release of the flip-flop FF5 is performed via the confirmation timer T6 after the state of M2 is released, the needle or the inlet valve is fully closed (74NL), and the turbine / generator is stopped (N142).

[0021]

According to the present invention, it is possible to detect damage to the deflector at an early stage in both the low-speed region and the high-speed region, so that a serious accident such as burnout of a brake or occurrence of a fire can be reliably avoided. Benefits are obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of a determination circuit for a water jet cutoff state;

FIG. 3 is a circuit diagram showing an abnormal signal and a brake release command output circuit.

FIG. 4 is an explanatory diagram for describing a first operation pattern of the water turbine / generator.

FIG. 5 is an explanatory diagram for explaining a second operation pattern of the water turbine / generator.

FIG. 6 is an explanatory diagram for explaining a third operation pattern of the water turbine / generator.

FIG. 7 is an explanatory diagram for explaining fourth and fifth operation patterns of the water turbine / generator.

FIG. 8 is an explanatory diagram for explaining a sixth operation pattern of the water turbine / generator.

FIG. 9 is a structural diagram for explaining the outline of the Pelton turbine.

FIG. 10 is a block diagram for explaining a relationship between a power system, a generator, and a speed detector.

[Explanation of symbols]

1, 4 servo motor, 2, 6 opening detector, 12 overspeed relay, 13 relay for specified speed, 141 relay for brake operation, 142 relay for stop detection, 31
Water pipe, 32, 32a ... branch pipe, 33 ... needle, 33
a: Needle s shaft, 34, 34a: curved pipe, 35,
35a ... nozzle pipe, 36, 36a ... nozzle, 37 ...
Runner, 37a: Runner bucket, 38, 38a: Deflector, AND1-13: AND gate, NOT1-1
0 ... not gate, T1-6 ... timer, FF1-5 ... flip-flop, OR1,2 ... OR gate.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masahiro Tanaka 1 Higashi-ku, Higashi-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. (58) Field surveyed (Int. Cl. ⁶ , DB name) F03B 1/04 F03B 15 / 18

Claims (1)

(57) [Claims] Claims: 1. In a hydroelectric power plant having a Pelton turbine, when a turbine / generator is stopped or when a deflector is discharged,
Detecting that a part or all of the water jet from the nozzle is blocked by the deflector, and holding means for holding the result, and monitoring the rotation speed of the turbine / generator in the state, A first detecting means for detecting that the water jet has been shut off, and also monitoring a rotation speed of the turbine / generator while the water jet is shut off, and once the rotation speed has once decreased to a specified speed, and again. Second detecting means for detecting that the rotation speed has risen beyond a prescribed speed; and also monitoring the rotation speed of the turbine / generator in a state where the water jet is shut off, and once the rotation speed has reached the braking operation. A third detecting means for detecting that the speed has increased to a speed higher than the brake operating speed again even though the speed has decreased to the speed and the brake has operated, and the water jet is also shut off. Monitoring the turbine / generator rotation speed in a state where it has been detected that the rotation speed has once decreased to the brake operation speed, the brakes have been activated, and the turbine / generator has stopped completely and has started to rotate again. A fourth detecting means for monitoring the rotation speed of the turbine / generator while the water jet is shut off, and confirming that the rotation speed does not decrease to a specified speed within a time that is predicted in advance. And a fifth detecting means for detecting, and outputting a deflector damage signal to the outside in response to any output from each of the detecting means, and outputting a brake release signal when the brake is being operated. Deflector damage detection device.