JPS5828430B2 - Suishiya Seigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hydraulic machine, mainly a water turbine generator.

The frequency of a hydroelectric power generation unit changes transiently in response to load changes, and the governor detects this frequency change and immediately adjusts the water turbine output to match the changed load. On the other hand, the water turbine output is accompanied by a time delay and exhibits an output opposite to the desired output during transient periods.

This phenomenon is due to the inertia of the water in the penstock, and will be explained below with reference to the drawings.

As shown in FIG. 1, 1 is a water wheel and 2 is a penstock, which is installed between the upper reservoir 3 and the lower reservoir 4 via the penstock 2.

5 is a guide vane of the water turbine, 6 is an inlet valve, and the artificial valve 6 is normally in a fully open position.

Here, the length of the same diameter part of the penstock 2 is Li (m), Li
Assuming that the average flow velocity of the section is V i (m/S), the effective head of the water turbine 1 is Ho (m), and the gravitational acceleration is g (m/S''), the above influence is ΣLiVi/H.

related to the size of

That is, if the guide vane 5 suddenly begins to close, the water pressure in the penstock 2 will rise rapidly, and the output P of the water turbine 1 will increase as if the head HO had increased by that amount.

Of course, after that, the water turbine output P gradually decreases and finally settles down to an output equivalent to the guide vane opening.

Further details are provided below.

If a penstock is expressed in early modern terms based on rigidity theory, it is P/Y.
-(1-Tw, D)/(]-+0.5TW, D) During operation at partial load, P/Y "" (1-(3o, Tw,
D)/(1+0.5Go, Tw, D)...
・・・・・・・・・・・・(1) Here, 'rw-(ΣLiVi)/Ho, gIn the above equation, P is the water turbine output (unit dimensionless, that is, 1 indicates the rated output), and Y is the guide vane. Opening degree (unit dimensionless, ie 1 indicates full opening).

Go is partial load (unit dimensionless, i.e. 1 indicates full load)
, D is Laplace parameter, Tw is time constant (sec)
It is.

Equation (1) is widely used as a theoretical stiffness equation for penstocks.

As is clear from equation (1), when the guide vane opening degree Y (speed governor output) is changed as shown in Fig. 2, the water turbine output changes in the negative direction for a while (times t1 and t2).
Thereafter, it rotates forward and gradually approaches the target value a.

That is, not only is the response of the water turbine output delayed with respect to the governor operation, but also the opposite output is produced transiently, which significantly impairs controllability.

A in FIG. 2 shows the response of the water turbine output when the guide vane opens in a curved shape, and the mouth shows the response of the water turbine output P when the guide vane opens in a step shape.

Conventionally, countermeasures have been taken to reduce the response speed by increasing the damping gain and time constant of the speed governor.

The conventional speed governor will be explained below with reference to the block diagram shown in FIG.

In the figure, Ec is a bias signal that becomes a load setting signal or a speed setting signal depending on the application. N is a speed signal, F is a signal Fσ representing the speed regulation rate of the speed governor, and a signal representing damping of the speed governor. It is an addition signal of Fδ, and E is a deviation signal between EC, F, and N, and is a signal for operating the speed governor.

Also, 60.61°62 is the signal addition point.

50 is a black box that represents a speed detection gain of 2, 51 is a black box that represents a hydraulic servo amplifier that performs an integral operation 1/D, and the input signal E is passed through the speed detection gain 50 and the hydraulic servo amplifier 51 as an output signal. Take the servo motor opening signal Y.

52 is a black box representing the speed regulation rate σ of the speed governor, 53 is a black box representing the damping δ(Tn, D)/(1+Tn, D) of the speed governor, and the servo motor opening signal Y is the speed regulation rate 52 and the damping 53 and are fed back to the speed governor inputs, respectively.

54 is a penstock (1-Go, Tw, D)/(1
+0.5Go, Tw, D), the servo motor opening signal Y is input to this penstock 54 as an input signal, the output signal is the water turbine output signal P, and at the 62 addition points, the water turbine output signal is The deviation signal between P and the load enters a black box representing the inertial effect 1/Tm, D of the 55 water turbine.

The signal that has passed through the inertia effect 55 of the water wheel is returned to the input of the speed governor as a speed signal N.

In addition, in the transfer function representing the damping 53 of the governor, Tn, D/(1+Tn, D) are differential forms, and the transient response is improved without having a gain in the steady state. It is something.

With the recent increase in the number of thermal power plants, the role of hydroelectric power plants as peak load governors is increasing, and the responsiveness of water turbine governors has become important.

Therefore, in conventional speed governors, high damping was applied before paralleling with the system for stabilization, and damping was removed after paralleling because it was easier to stabilize. If damping had been similarly excluded at the power plant after paralleling with the grid, there is a possibility that the stability of the entire system would be compromised and a vibration accident would occur in the entire system.

Therefore, we wonder if there is a relationship between the influence of the penstock and damping, which causes a decrease in the stability of the control system.

Figure 4 is a bluff published by Hiroshi, M. and HOVEY, showing the stability of the plant with respect to the time constant Tw of the penstock, the time constant Tm of inertia, the damping gain δ, and the damping time constant Tn.

Here, Tm WR2 No 2

As is clear from FIG. 4, increasing the damping gain δ or the time constant Tn stabilizes the control system, but on the other hand, as shown in FIG. 5, the governor-like time constant Tg gradually increases.

That is, the response speed gradually becomes slower. The exclusion of damping after parallelization with the grid was born from this background, but there is a problem with the stability of the entire grid as described above.

If the water pressure in the iron pipe is the cause of instability, possible countermeasures include increasing the inner diameter of the penstock to lower the water flow velocity, or installing a surge tank or pressure suppressor, but this would not only be extremely expensive, but also The equipment will also be complicated.

The purpose of the present invention is to increase the response speed of the governor without reducing the high damping commensurate with the influence of the penstock, in order to reduce the instability of the plant due to the inertial effect of water in the penstock. That's what I did.

The gist of the present invention is a speed governor that keeps the rotational speed of a water turbine constant regardless of load fluctuations, a husband's circuit that inputs a load setting signal and a speed signal to the speed governor, and a water turbine load fluctuation. A differentiation circuit is provided in parallel with the circuit for differentiating at least one of the hourly load setting signal and the load signal and inputting the differentiated signal to the speed governor. By adding the signal, the speed governor can respond quickly without delay when the load fluctuates.

Considering the differential value of a changing load means looking at whether the load is changing rapidly or slowly, and considering that if the load is changing rapidly, it is inevitable that it will change more greatly. In this way, the aircraft can respond greatly in advance to enable advance control.

Of course, when the load fluctuations become gradual and are becoming stable, the signal is also reduced to prevent the governor from performing excessive control.

In other words, differentiation makes predictions easier, and the more you consider higher order differentiation, the better the prediction will be.

Also, when considered in terms of frequency response, it acts as a phase recovery.

As a result, not only the transient response speed can be improved, but also the stability of the entire control system can be improved at the same time.

We expected similar predictions when considering the differentiation of the load setting signal.

However, in this case, the load setting signal itself is a -m disturbance to the speed governor control system under consideration, and therefore has no bearing on the stability of the system.

Next, the present invention will be explained with reference to FIG.

In the block diagram of Figure 6, 50~55°60~6
2 is the same as the conventional example shown in FIG.

Reference numeral 56 denotes a black box representing a load detector, which detects the load and converts it into a load signal Ew.The load signal Ew is also sent to a differentiating circuit represented in the black box as a quick response improvement amplifier 57. , the output signal Ewc of the responsiveness improvement amplifier 57 is led to the addition point 60 as one of the speed regulating input signals.

As shown in FIG. 8, the responsiveness improvement signal Ewc is a signal that is generated only transiently when the load setting signal EC as an input signal or the load signal changes, and gradually decreases to zero as time passes.

Therefore, since the responsiveness improvement signal Ewc is zero during steady state,
This is similar to the conventional example shown in FIG.

That is, the transfer function, KL, TL, D/(1+TL, D)
Since the quick response improvement amplifier 57 consisting of a differentiating circuit represented by is of a differential type, the input signals EC and E of the quick response improvement amplifier are
By generating the output signal Ewc transiently only when w changes, it only affects the input signal of the governor, and the stability of the system is not affected at all. The damping settings for anxiety factors can be maintained without changing.

In other words, in the steady state, the gain is not modified, and the gain is provided only for the purpose of improving transient response.

In the governor shown as a conventional example in FIG. 3, the response of the servo motor opening signal Y to the governor-like input signal entering the addition point 60 is very slow as shown by the solid line in FIG. As shown in FIG. 9, if the speed governor input signal that enters the addition point 60 only transiently when the load is set or changes is made sufficiently large, the response of the servo motor opening signal Y will be as shown by the dotted line in FIG. The desired speed can be achieved.

Next, an embodiment based on the present invention will be described with reference to FIG.

The water turbine 101 and the generator 102 are integrated with a generator shaft 103, and the rotational speed of the water turbine is determined by a speed signal oscillator 104 provided on the generator shaft 103 and a magnetic pickup 10.
5, it is converted into a pulse signal by the speed detection amplifier 106.
The pulse signal is converted into a DC voltage, amplified, and transmitted as a speed signal N to the input resistor 101 of the amplifier 109.

This speed signal N is then amplified by an amplifier 109 and applied to a solenoid coil 110.

The solenoid coil 110 is an amplifier. The strength of the magnetic field is changed according to the increase/decrease in the output of the magnet 109, and a displacement proportional to this magnetic force is given to the magnet 111.

The pilot plunger 112 connected to the magnet 111 is moved up and down in accordance with this displacement, producing a relative displacement with the pilot sleeve 113, thereby opening and closing the flow of pressure oil supplied to the servo piston 118.

For this reason, the pressure oil 114 is gushed into either the oil pipe 115 or 116, and the other is drained, so the servo piston 118 moves left and right to change the opening degree of the guide vane of the water turbine 101, thereby adjusting the amount of water. Adjust the water wheel rotation speed to keep it constant.

Furthermore, the movement of the servo piston 118 is controlled by the servo piston 11.
A voltage proportional to the opening degree of the servo piston 118 is transmitted to the potentiometer slide 120 by displacement between the potentiometer slide 120 provided on the arm 119 directly connected to the servo piston 119 and the potentiometer resistor 121.

This voltage is applied to the input resistor 126 of the amplifier 109 through the speed regulation rate potentiometer 125, and is also applied to the input resistor 124 of the amplifier 109 through a damping circuit consisting of a capacitor 122 and a potentiometer 123. The signal voltage is the input resistance 10
7 is fed back to the speed governor as a compensation signal for the speed signal voltage given to the speed signal voltage.

Here, the potentiometer 125 and input resistor 126 are set to correspond to the speed regulation rate of 52 in the block diagram of FIG. 6, and the capacitor 122, potentiometer 123 and input resistor 124 are set to correspond to the damping of 53 be done.

The response of the servo piston 118 to the displacement of the pilot plunger 112 is determined by the hydraulic servo amplifier 1/D at 51.
The integral characteristic l is expressed as .

The howl detection section from the speed signal oscillator 104 to the human resistor 107 is represented by a speed detection gain of 2 at 50.

The part surrounded by the dotted line is the part related to the present invention,
This corresponds to the addition point 63 of the load signal R and the load setting signal Ec and the responsiveness improvement amplifier 57 in FIG.

In the embodiment, the load setting signal Ec and the load signal Ew obtained by detecting the load signal from the generator 102 with the load detector 128 and converting it into a DC voltage are connected to the resistors 129 and 13, respectively.
131 and an amplifier 132, and its output signal is input to an adder consisting of a resistor 133, 135, a capacitor 134, and an amplifier 132.
Transfer function KL consisting of amplifier 136.

TL, D/(1+TI, , D) is generated by the immediate response improvement amplifier 57 that constitutes a differentiating circuit that satisfies the following.

This responsiveness improvement amplifier 57 receives input signals Ec and E.
Amplifier 1 on the governor-like input side uses the readiness improvement signal EWC, which is amplified in transient response when w changes, as an output signal.
It is provided to the input resistor 137 of No. 09, and is designed so that no output signal is generated during normal operation.

Further, 138 is a resistor for setting the load, and the load setting signal EC is applied to the input resistor 130 of the adder 132 and the human resistor 12γ of the amplifier 109 at the speed governor input end.

According to the present invention, while maintaining high damping for stability due to the inertia effect of the penstock, the response speed can be increased by adding a signal corresponding to the load fluctuation speed I, so it is not stable as before. This achieves the effect of being able to resolve the contradictory issues of stability and quick response, in which high damping is used to improve stability and quick response is reduced.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the water turbine and penstock, Figure 2 is an explanatory diagram showing the influence of the penstock on the water turbine output, Figure 3 is a block diagram of a conventional governor control system, and Figure 3 is a block diagram of a conventional governor control system. Figure 4 is a diagram of the relationship between the damping setting value of the speed governor and the stability of the system.
The figure shows the relationship between the damping setting value of the speed governor and the response speed.
Fig. 6 is a block diagram of the governor control system based on the present invention, Fig. 7 is a simplified diagram of an embodiment to which the present invention is applied, Fig. 8 is an explanatory diagram of differential characteristics, and Fig. 9 is a quick response diagram. It is an explanatory diagram. Sign confusion, 50... Howl detection gain, 51.
... Hydraulic servo amplifier, 52 ... Howling adjustment rate of speed governor, 53 ... Damping of speed governor,
54... Penstock, 55... Inertia effect of water wheel, 56... Load detection, 57...
Immediate response improvement amplifier, 60-63...Signal addition point, 128...Load detector, 129-131...
...Resistance, 132...Amplifier, 133...
...Resistor, 134 ...Capacitor, 13
5...Resistor 136...Amplifier, 137
...Input resistance, 138...Load setting resistance.

Claims (1)

[Claims] 1. A speed governor that keeps the rotation speed of the water turbine constant regardless of load fluctuations, respective circuits that input load setting signals and speed signals to this speed governor, and load setting signals and load signals during load fluctuations of the water turbine. and a differentiating circuit installed in parallel with the circuit for differentiating at least one of the signals and inputting the differentiated signal to the speed governor. A water turbine control device characterized in that the water turbine control device is added as an input signal to a speed governor via a speed governor.