JP2008161022A - Hydraulic power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic power generator using control for restraining rapid torque fluctuations to a waterwheel and an AC generator by preventing the AC generator from being powered for running when engine speed of the waterwheel is controlled in the power generator. <P>SOLUTION: In the hydraulic power generator having at least the waterwheel, the AC generator jointed with the waterwheel, and an inverter for controlling the AC generator as constitutive elements, the inverter is controlled so that the AC generator is not powered for running, an engine speed command to the AC generator at start is gradually reduced from a high speed side, and the engine speed command to the AC generator at stop is gradually reduced to the high speed side. When the AC generator 3 stops, the engine speed command n* is gradually increased to a non-signal reference side, the water amount is decreased, thus restraining unnecessary torque fluctuations to the waterwheel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a hydroelectric generator, and more particularly, to a hydroelectric generator using a control that suppresses sudden torque fluctuations of a turbine and an AC generator when controlling the rotational speed of the turbine.

In general, in a dam or the like, it is necessary to always discharge a predetermined amount of water in order to maintain downstream irrigation even if the head fluctuates. Hereinafter, this is referred to as maintenance discharge. In addition, hydroelectric power generation is performed using this amount of water and the head to effectively use natural energy.

In order to achieve both maintenance discharge and hydropower generation efficiently, it is necessary to adjust the amount of water in order to maintain a constant amount of water even if the head fluctuates. This is generally dealt with by adjusting the opening of the turbine inlet valve and adjusting the angle of the turbine blade. However, the mechanism is complicated and there is a restriction that the adjustment range cannot be widened due to the limitation of the system frequency. (For example, Patent Document 1)

On the other hand, there is a method of controlling the number of rotations of the water turbine as another method of adjusting the amount of water. In other words, the amount of water can be adjusted by controlling the number of revolutions of the AC generator using an inverter in a hydroelectric power generation system comprising at least the components of the turbine and the AC generator connected to the turbine and the inverter that controls the AC generator. it can. In addition, according to this configuration, since the AC generator is not directly connected to the system, there is an advantage that the AC generator speed is not limited by the system frequency and the adjustment range can be selected widely.

The rotation speed control by the inverter of the AC generator uses the deviation between the rotation speed command and the actual rotation speed as a torque command via the speed controller, and controls the AC generator current so that the deviation between this and the actual torque is eliminated. It is done by doing.
The direction of the torque of the AC generator at the time of power generation in the rotational speed control is usually the brake torque (absorption torque).

However, when the head is extremely low, or when it is excessive such as acceleration during operation and deceleration during stoppage, the rotational speed is controlled, so the direction of the torque may be reversed and the AC generator may be powered. In this power running operation, energy goes from the AC system to the turbine, and the turbine operates as a pump. In power generation operation, energy is sent from the turbine to the AC system.
Depending on the type of turbine, switching to the power running side causes a large torque fluctuation and a poor condition, and the turbine is required to have a control method that does not cause power running in any case.
JP 2000-102295 A

The object of the present invention is to solve the above-described problems and to prevent the alternator from performing a power running operation when controlling the rotation speed of the turbine in the power generation device having the above-described configuration. An object of the present invention is to provide a hydroelectric generator using control that suppresses sudden torque fluctuations.

In order to achieve the above object, according to a first aspect of the present invention, in a hydroelectric generator comprising at least the constituent elements of a water turbine, an AC generator connected to the water turbine, and an inverter for controlling the AC generator, The inverter is controlled so that the generator is not powered.

According to claim 2, in the hydroelectric generator having at least the constituent elements of the water turbine, the AC generator connected to the water turbine, and the inverter that controls the AC generator, a rotational speed command to the AC generator at the time of starting is issued. It is characterized by gradually decreasing from the high speed side.

According to claim 3, in the hydroelectric generator having at least the constituent elements of the water turbine, the AC generator connected to the water turbine, and the inverter that controls the AC generator, the rotational speed command to the AC generator at the time of stop is issued. It is characterized by gradually increasing toward the high speed side.

As will be described later, conventionally, when the AC generator 3 (water turbine 1) is started, the rotational speed command n * is gradually increased from the signal reference (0V) side to the counter-signal reference side in accordance with the increase in the amount of water due to the opening of the inlet valve. The car was running when it reached the specified speed. In this method, depending on the relationship between the gradual increase in the rotational speed command n * and the increase in the amount of water, the turbine may repeatedly switch between no-load operation and power generation, which may cause unnecessary torque fluctuations and adversely affect the turbine. was there.

According to the present invention, when the AC generator 3 (water turbine 1), which will be described later, is started, the rotational speed command n * is moved to the counter signal reference side in advance, and the water amount is increased by opening the inlet valve. As a result, the turbine speed is reduced from the no-load operation to the power generation operation smoothly without repeating unnecessary switching between the no-load operation and the power generation operation by gradually decreasing the rotational speed command n * to the signal reference (0V) side. Instead, unnecessary torque fluctuations can be avoided.

Further, according to the present invention, when an alternator 3 (water turbine 1), which will be described later, is stopped, the amount of water is reduced while gradually increasing the rotational speed command n * to the counter signal reference side, thereby eliminating unnecessary water turbines. Torque fluctuation can be suppressed.

The details of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration example of the present invention. 1 is a water wheel, 2 is a gear, 3 is an AC generator, 4 is an inverter, 5 is an interconnection inverter, and 6 is an AC system.

The water turbine 1 converts hydraulic energy into rotational energy, and the alternator 3 further converts it into electrical energy. The inverter 4 is for appropriately controlling the torque generated by the AC generator 3, whereby the rotational speed of the AC generator 3 (water turbine 1) is appropriately controlled, and the electric energy converted by the AC generator 3 is connected. Send to system inverter 5. The interconnection inverter 5 sends the sent energy to the AC system 6.

The gear 2 may be unnecessary as a mechanism for matching the rotational speeds of the water turbine 1 and the AC generator 3.
Since the inverter 4 and the interconnected inverter 5 are connected by direct current, it is clear that the rotational speed of the AC generator 3 and the frequency of the AC system 6 are irrelevant and do not interfere with each other. Further, the type and type of the water wheel 1, the presence or absence of the gear 2, and whether the AC generator 3 is an induction generator or a synchronous generator does not change the effectiveness of the present invention.
Note that control between the inverter 4 and the interconnected inverter 5 and between the interconnected inverter 5 and the AC system 6 is not related in the present invention, and thus the description thereof is omitted.

FIG. 2 shows a conventional example of a control block of the inverter 4 having the configuration shown in FIG. In FIG. 2, n * is a rotational speed command, n is a rotational speed feedback from a rotational speed pickup (not shown), 7 is a rotational speed controller, τ * is a torque command, and τ is a torque feedback, not shown. It is calculated by the calculation unit. 8 is a torque controller, and this output becomes a current command i * and is sent to a current controller (not shown). The torque command τ *, which is the output of the rotational speed controller 7, has a positive or negative polarity depending on the magnitude relationship between the rotational speed command n * and the rotational speed feedback n.

In other words, the rotational speed is controlled by having both positive and negative polarities. If the positive side of the torque command τ * is made to correspond to the brake torque, the negative side becomes the power running torque. Therefore, when the torque command τ * becomes negative, the AC generator 3 (water turbine 1) is operated in a power mode, and the torque fluctuation increases correspondingly, resulting in an undesired operation mode for the water turbine.

FIG. 3 shows an embodiment of the present invention in which the above-mentioned problems are solved. Those having the same functions as those in FIG. 2 are denoted by the same numbers or the same symbols. Reference numerals 9 and 10 denote diodes, and the anode of the diode 10 is connected to a signal reference (0 V).

Further, the diode 9 and the diode 10 have their cathodes connected in common, so that a large signal on the positive side is given priority, so that the torque command τ * can be prevented from becoming negative after all.
In the actual configuration, the priority configuration of the diode 9 and the diode 10, and the control configuration of each controller, etc. are configured by an operational amplifier or a digital arithmetic unit, but the effect of the present invention is not different by the realization means.

Since the torque command τ * does not become negative, the AC generator 3 (water turbine 1) does not perform power running, and the torque fluctuation is reduced accordingly, which is a preferable operation mode for the water turbine.

FIG. 4 shows an embodiment of the rotational speed command of the present invention. Those having the same functions as those in FIGS. 2 and 3 are denoted by the same reference numerals or symbols. Reference numeral 11 denotes a setting device having an electric mechanism, and both ends thereof are connected to a signal reference (0 V) and an appropriate potential. The electric potential of the slider is changed by the rotation of the electric motor, and the rotation speed command n * is obtained. When the slider of the setting device 11 is the signal reference (0 V), the rotation speed command is set to zero, and when the slider is on the counter signal reference side, the rotation speed command is associated with the maximum rotation speed command.

Although the setting device 11 has been described with an electric mechanism in the embodiment of the present invention, it goes without saying that the setting device 11 can also be configured by software, and the effect of the present invention can be achieved regardless of the means of realization.

FIG. 1 shows a configuration example of the present invention. FIG. 2 shows a conventional example of a control block of the inverter 4 having the configuration shown in FIG. FIG. 3 shows an embodiment of the present invention in which the above-mentioned problems are solved. FIG. 4 shows an embodiment of the rotational speed command of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waterwheel 2 Gear 3 Alternator 4 Inverter 5 Interconnected inverter 6 AC system 7 Speed controller 8 Torque controller 9 Diode 10 Diode 11 Setting device

Claims (3)

In a hydroelectric generator having at least constituent elements, a water turbine, an AC generator connected to the water turbine, and an inverter for controlling the AC generator, the inverter is controlled so that the AC generator does not power. Hydroelectric generator. 2. The hydroelectric generator according to claim 1, wherein a rotational speed command to the AC generator at the time of starting is gradually reduced from a high speed side. 2. The hydroelectric generator according to claim 1, wherein a rotational speed command to the AC generator at the time of stop is gradually increased toward a high speed side.

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