JPH01163474A - Control method for operation of variable speed water turbine - Google Patents

Abstract

PURPOSE:To enable the smooth and sure changeover of a mode by shifting the mode while holding a rotating speed in the vicinity of the lower limit within a variable speed band at the time of the changeover from an idling operation mode to a power generating operation mode. CONSTITUTION:When the variation in the frequency (f) of an electric power system is large during an idling operation, the temporary following variation of an effective electric power P is permitted. Hence, it is necessary to give due consideration to not making the comparison element or integral element gain in a speed control portion 31 excessively large. As the result of thus restricting the response speed of a speed control system, although the temporary variation in rotating speed N is unavoidable, normal operation can be continued so far as the rotating speed N is within a variable speed band. If the rotating speed tends to get off of the variable speed band, the holding in the variable band is carried out by means of a kick-back circuit 42.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies the so-called 8-character characteristic NI (however, Q
It's like a waterwheel! ? t) or TI= (where T is the water turbine ■ (generated torque) of the water turbine has the characteristic of decreasing, and relates to water turbine equipment that is capable of variable speed power generation, in particular, is capable of idling operation, and is an operating mode from idling to power generation. The present invention relates to a control method suitable for minimizing disturbance to the power system during switching.

[Conventional technology]

The following are known examples of the present invention.

a, Electric Power Technology Handbook (Denki Shoin, partially supervised by Professor Hanino, Waseda University) pi-64, 7, 5, 3, p5-819.4, JP-A-6L-170300 C1 Special Publication 6L-31312 d, 1028 "Study of two-axis excitation current control system of generator motor for variable speed pumped storage power generation system" presented at the National Conference of the Institute of Electrical Engineers of Japan in 1961 It has been described. However, there is no mention of a harmonic operation control method for variable speed hydraulic machines equipped with power converters and capable of variable speed operation.

FIG. 7 is a block diagram of a control device according to a known example.

The water turbine characteristic function generator 5 has a power generation output command Po and a water level detection
The output signal H is input, and the optimum rotational speed command Na and the optimum guide valve opening command Ya are calculated here. The optimum rotational speed command N& is compared with the actual rotational speed signal N detected by the rotational speed detector 6 by a comparator 10, and the deviation ff1Na is compared with the actual rotational speed signal N detected by the rotational speed detector 6.
(=Na−N) is input to the arithmetic unit 11. Arithmetic unit 11
are proportional element CI), integral element Cr/S, and differential element Cos.
and an adder 12, which outputs a correction signal ΔY for correcting the optimum guide valve opening command Y& so as to reduce the deviation ENa to zero as long as the deviation ENa exists. This correction signal ΔY is added to the optimum guide valve opening command Y& in the adder 13.
The output from , that is, the corrected guide valve opening command (ya
+ΔY) is input to the guide valve drive device 8. The guide valve drive device 8 consists of an adder 14 and an integral element of 4/S, the output of which is negatively fed back to the adder 14. The power generation output command Pxo is also input to a comparator 15, and is compared with the actual power generation output signal P detected by the power generation output detector 16, which is the other input, and its deviation ΔP (=Pxo-P) is calculated. is input to the power control device 17. The power control device 17 includes a proportional element Ka, an integral element Ke/S, and an adder 18, the output of which is input to the cycloconverter 3.

According to this known example, in this control device, if, for example, the power generation output P is to be increased in a stepwise manner at a time point to, the power generation output command Pxo is increased in a stepwise manner as shown in FIG. 8(a). The power generation output P of the generator 1 is
As shown in FIG. 8(g), it increases following the change in the power generation output command Pxo. That is, the integral element Ke/S included in the power control device 17 and the power control device 17. Due to the negative feedback circuit constituted by the cycloconverter 32, the generator 19, the generated output detector 16, and the comparator 15, the deviation ΔP=(Pxo-P) gradually decreases to P:P in steady state.
It becomes xo. On the other hand, the responsiveness of the opening Y of the guide valve 9 to the optimum guide valve opening command Ya is the above-mentioned power generation output command Px
It is slower than the response of the power generation output P to o. For this reason, the water turbine output Pt becomes smaller than the power generation output P, and as shown in FIG. 8(f), the rotational speed N is
After the sudden change in xo, the speed is decelerated temporarily, and then, as shown in FIG. 8(d) at time t1, the guide valve opening Y becomes equal to the optimum guide valve opening command Ya, and the power generation output P and the water turbine Output PT
Since these become almost equal, the rotational speed N stops decreasing. Note that at time tl, the actual rotational speed N is lower than the optimum rotational speed command Na, the deviation εsa= (Na N) is positive, and the correction signal ΔY output from the calculator 11 is positive. Guide valve opening command corrected by correction signal ΔY (
ya+ΔY) becomes larger than the optimum guide valve opening command Y&, and eventually the water turbine output PT becomes larger than the power generation output P. Therefore, the rotational speed N increases and the optimum rotational speed command N&
, the correction signal ΔY also approaches zero, and finally the guide valve opening Y becomes equal to the optimum guide valve opening command Y&, and the rotational speed N becomes equal to the optimum rotational speed command Na. That is, the integral element Ct/S included in the arithmetic unit 11 and the arithmetic unit 11. Adder 13, guide valve drive device 8. Guide valve 9. A negative feedback circuit composed of a water turbine 22, a generator 12, a rotation speed detector 6, and a comparator 10 allows the deviation εNa"Dya
-N) gradually decreases until N = Na at steady state. In addition, during steady state, the deviation ΔY=(Y-Ya)=O1, that is, Ya'':Y is achieved as follows: (a) Optimal guide valve opening command Y output from the water turbine characteristic function generator 5
Of course, a corresponds to the power generation output command Pxo. (b) As mentioned above, steady state P: P
It becomes o. (c) The inertia effect of all rotating parts such as the rotor of the run 1 generator 1 of the water turbine 2 is accelerated or decelerated by the difference between the water turbine output Pt and the generated output P, and is a kind of integral In addition, as described above, since a negative feedback circuit is constituted by 11.13, 8, 9, 2, 1, and 6.10, Pt=P in steady state. (d) The guide valve opening degree Y corresponds to the water turbine output PT. If we combine the above (a) to), the deviation Δy=
(y-ya)=0, that is, Ya''Y.

That is, the known example discloses a preferable control method in the power generation mode of a variable speed hydroelectric power generation device.

In particular, it is preferable to control the rotational speed by mechanical output control on the water turbine side rather than electrical output control on the generator side, and introduces a specific example.

However, this known example does not mention at all the idling operation mode or the idling→power generation mode switching, which is the object of the present invention.

In known example C, when switching from the idling mode of rotation in the direction of the water turbine, especially the harmonic mode that performs reactive power control, to the power generation mode, the generator is disconnected from the power grid, the rotational speed of the water turbine is lowered once, and then the guide vanes are opened. This disclosure discloses a control method for accelerating the vehicle again and rejoining the synchronized upper power grid.

Incidentally, like the present invention, this known example was also invented keeping in mind the eight-character characteristics of water turbines.

However, this method requires cumbersome operations and controls such as disconnecting from the power grid, resynchronizing, and reconnecting at the time of switching, which not only degrades system reliability but also lengthens the switching time, which is a decisive flaw. There is.

Furthermore, when attempting to switch from phase modulation mode to power generation mode, the power system is demanding the earliest possible supply of active power, and the wasted time during this time significantly reduces the contribution of this plant to the power system. be.

Note that this known example C does not mention the variable speed power generator at all.

Further, Publication Example d discloses a two-axis exciting current control method for a generator motor for a variable speed pumped storage power generation system.

FIG. 5 is an explanatory diagram of this, in which the secondary side, that is, the rotor side of the generator/motor 1 is subjected to variable frequency excitation by the power converter 3 (CYC), and the power frequency on the primary side, that is, the stator side of the generator/motor 1 is adjusted. This relates to variable speed power generation/electric fullja in which the rotational speed of the rotor is made variable while being held constant. The APR (output control device) 17 compares the output command (i.e., active power command) not shown in the figure with the output of the actual output detector 16, and calculates the effective power equivalent that should be for the ACR (exciting current control device) 37. command the value Iq of the direct axis current.

On the other hand, an AVR (voltage control device) 36 compares a voltage command (not shown) with the actual generator/motor voltage detected by the voltage detector 39 and commands a horizontal axis current value i- corresponding to the voltage that should be.

ACR (exciting current control device) 37 is as described in i.

i, the actual slip phase angle O8 detected by the phase detector 7, and the actual phase current i, each phase voltage command V
decide.

Note that 38 is a current detector for the generator/motor, and 40 is a transformer for the three power converters. By the way, this known example does not mention at all a method of controlling a hydraulic machine during idling operation.

[Problem that the invention seeks to solve]

The problem of the present invention is to solve the problem of mode switching from idle mode to power generation mode in a variable speed power generation plant, which is a new problem that has never been touched before. ) or prevent an abnormal drop in the rotational speed of a water turbine, and enable smooth and reliable mode switching.

Furthermore, it is possible to perform switching in a short time without losing time due to disconnection, etc., thereby increasing the degree of contribution to the power system.

In addition, it is necessary to provide a switching control method that is well suited to the control situation in the idling, two-generation, and two-generation operation modes.In particular, in the idling operation mode, it is possible to perform not only reactive power control but also active power control, and in the generation mode, the rotation speed is changed to the water turbine side. To provide a switching method suitable for a system that uses

[Means for solving problems]

(1) First, the rotational speed of the water turbine is maintained near the lower limit of the variable speed band while switching from idle to power generation mode (especially until the runner chamber is filled with water and the guide vanes are fully opened to near the no-load opening position).

(2) When the guide vanes have finished opening to around the no-load opening degree, the rotational speed control is switched from control based on the drive output on the generator side to control using the guide vanes on the water turbine side.

(3) The target rotation speed during idle operation is set near the center of the variable speed band, and is moved to near the lower limit of the variable speed band when switching to power generation mode.

(4) During idling operation and during switching, the same speed control system is used that controls the drive output of the generator to match the rotation speed to the target value, but the time constant of the control system is different during idling operation. long,
Set the switching to be short during switching.

[Effect]

The effects of each of the above measures are as follows.

Omega! Uro LL Before getting into the main topic, I will explain the 8-character characteristics.

Generally, the runner of a pump-turbine, especially a high-head pump-turbine, is designed to exhibit sufficient centrifugal pumping action in order to obtain a high head during pump operation.

However, this design adversely affects the turbine operation of the pump turbine. In particular, it is considered inevitable that a characteristic called the 8-character characteristic, which will be described later, is accompanied.

When the characteristics of the pump-turbine adopted in this design are shown by a characteristic curve representing the relationship between the number of revolutions per unit head (N1) and the flow rate per unit head (Qz) under a predetermined guide vane opening, this characteristic The curve has a first part in which the value of Ql decreases as the value of N1 increases and a second part in which the value of Ql decreases as the value of N1 decreases in the turbine operation region.
It has a part. For convenience of explanation, the second portion is referred to herein as the character eight characteristic portion. Furthermore, 8
The characteristics of the pump-turbine in the character-shape characteristic portion are hereinafter referred to as the character-eight characteristics. Regarding water turbine operation in the character 8 characteristic part,
The torque per unit head (T1) also decreases as the number of revolutions per unit head (Ni) decreases.

Decrease.

A pump with figure 8 characteristics in the water turbine operation area.

The characteristics of the water turbine are shown in Figures 6A and 6B.

In Figure 6A, the characteristics of the pump-turbine are determined by the number of revolutions per unit head (N1) using the guide vane opening as a parameter.
and the flow rate per unit head (Ql). On the other hand, in Figure 1B, the characteristics of the pump-turbine are determined by the same parameters as the number of revolutions per unit head (N
1) and torque per unit head (Tz). Nl t Qt and T1 are expressed by the following equations.

Nx” N//7Tr-Qt=Q//Tr
, T t= T/H In the above formula, the symbols N, Q,
H and T are the rotation speed and flow rate of the pump turbine, respectively.
Indicates effective head and torque.

Characteristic curves 101 and 101' are obtained under certain relatively large guide vane openings. Characteristic curves 102 and 1
02' is obtained under a smaller guide vane opening. Characteristic curves 103 and 103' are also obtained at smaller guide vane openings.

In the a-dh portion of the characteristic curve 101, the value of Ql decreases as Nl decreases. As mentioned above, this curved portion a-d-h is referred to herein as the figure-eight characteristic portion. Similarly, curve portion b-e-i is a character-eight characteristic portion of characteristic curve 102, and curve portion c-f-
j is the figure 8 characteristic portion of the characteristic curve 103. - As can be seen, the 8-character characteristic portions a-d of the characteristic curve 101
-h is the 8-character characteristic portion b of the characteristic curve 102 -e -i
longer, the 8-character characteristic part b −e − of the characteristic curve 102
i is longer than the 8-character characteristic portion c − f − j of the characteristic curve 103. This means that when the guide vane opening becomes smaller, S
This means that the length of the character characteristic part becomes shorter.

As in FIG. 6A, in FIG.
and c/-fl-j/ are the characteristic curve 1', respectively
, 2' and 3'.

6B has a close relationship with FIG. 6A. For example, a point corresponds to point X'. Point X' is Tl=TIX' t Nt:
This is a point that satisfies NIX' (=Ntx).

Similarly, points a, b, C9d, e in FIG. 6A.

f, h, i and j are respectively points a' in FIG. 6B.
, b', C', d', e', f', h'.

It corresponds to i' and j'.

Curve nr is a no-load flow rate curve. The intersection points α, β, and γ of curve 1゜2.3 and curve nr are each 1 curve 1'
, 2', 3' and the straight line Ti=O at the intersection α', β'
, γ′.

By the way, the opening degree of the inner blade is the characteristic curve 103 and 103'.
Let's consider a case where the rotational speed increases or H decreases and Nl increases from this state, assuming that Nx''-, /T is at NIL.

The operating point on the N1 Qt curve in FIG. 6A is initially 2, but moves to γ and then to C as N1 increases.

On the NI Ti curve in FIG. 6B, it moves from 2' to γ' to C'.

Then, when it reaches C, it enters the 8-character characteristic and JP-A-61
-For the reason detailed in 170300, instead of N1 increasing, the flow rate Q drastically decreases, and instead decreases (accompanied by an increase in H), and the pull-back operating point naturally becomes c-*f→j. I feel deeply depressed.

That is, even though the water wheel is rotating in the direction of the water wheel, the flow shifts to a negative flow, that is, a pump flow. Similarly, in FIG. 6B, the operating point naturally falls sharply from C' to f' to j', and the driving load on the generator rapidly increases. By the way, as can be seen from the figure, the guide vane opening at which the generator output becomes zero, ie, the no-load opening, decreases as the operating Nl decreases.

When NZ becomes sufficiently low, for example Nl, the no-load opening becomes equivalent to curves 104 and 104'.

When the opening is small like that, curves 104 and 10
4', the above-mentioned 8-character characteristic disappears, and there is no need to worry about sudden drops in flow rate or turbine torque.

As can be seen from the above explanation regarding the figure 8 characteristic, if N1 is sufficiently low when the water turbine is placed in an unloaded state, there is no need to worry about the figure 8 characteristic.

That is, means (1) avoids the pump flow in the process of transition from idle operation to power generation operation without being affected by the figure-8 characteristic, and makes it possible to avoid a phenomenon in which the generator output greatly drops to the negative side.

(L) When the guide vane has finished opening to near the no-load opening, the rotational speed can be immediately increased by opening the guide vane even slightly, and the rotational speed can be immediately decreased by closing it even slightly. If you change the mode before the opening is completed to the no-load opening, and for some reason the rotational speed starts to decrease at this time, the rotational speed cannot be corrected until the guide vanes are opened to the no-load opening, and the rotational speed is still falling during this time. This is undesirable as it increases the

Also, if the guide vane opening exceeds the no-load opening, the rotational speed can be controlled by simply increasing the electrical load on the generator, that is, the generator output, by the amount of over-opening that exceeds the no-load opening. .

During idling operation, it is desirable to simultaneously perform active power control, which acts to suppress frequency fluctuations in the power system, in addition to reactive power control, as will be described in detail later.

As a result, the rotational speed may transiently swing upwards, upwards, or downwards from the target value, but in order to keep the swing margin as wide as possible both above and below within the predetermined variable speed band, the target value must be changed to a variable speed. It is best to set it near the center of the band.

On the other hand, when switching from idling to power generation, it is necessary to move the target value of the rotational speed to near the lower limit of the variable speed band, as explained in the effect (1) above. That is, the setting of the target rotation speed should be changed at the time of mode switching.

If the time constant is long, the response of the rotational speed control system will be slow. That is, when the active power is corrected in response to fluctuations in the power system frequency, the rotational speed deviates from the target value and swings upward or downward, but it takes a long time for it to return to the original target value. However, on the other hand, it means that the active power control in response to the power system frequency can be shared in a larger proportion.

On the other hand, if the time constant is made too small, even if the active power is corrected in response to frequency fluctuations in the power system, the control that attempts to suppress rotational speed changes will respond too quickly, making it difficult to use the effective power correction signal. It acts to kill.

Therefore, during idling operation, the time constant of the rotational speed control system is set to be long. On the other hand, during the transition from idling to power generation, the original rotation speed is intended to be maintained near the lower limit of the lower shift band and must not be lowered any further, so the time constant of the rotation speed control system should be set to a short value. .

【Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. 1 indicates an induction generator that can be used as both a generator and an electric motor; 2 indicates a hydraulic machine directly connected to the rotor of the generator 1;
3 is a power converter, that is, a cycloconverter that provides variable frequency excitation corresponding to the slip in the secondary excitation circuit of 1 generator, 6 is a speed detector that detects the actual rotational speed N of the hydraulic machine, and 7 is a slip phase detector A slip phase angle θS, which is equal to the difference between the voltage phase of the primary side of one generator, that is, the power system, and the rotational phase of the secondary side of one generator expressed in electrical angle, is detected by the device.

The rotor of the slip phase detector is provided with three phase windings connected in parallel with the primary winding of the generator, and the stator side of the slip phase detector is provided with three phase windings at positions different by π/2 in electrical angle. One Hall converter is provided for each, and a signal in which the voltage phase of the power system as seen from the secondary side of one generator matches is detected by the Hall converter, and the slip phase angle U is detected by the Hall converter.
converted to s.

Noz is the target speed during idling operation of the hydraulic machine and is selected near the center of the variable speed band. On the other hand, Not is set to a value near the lower limit of the variable speed band at the target speed during switching from idling to power generation. The switch 29 performs switching according to the NOl and Not operation modes.

30 is an adder for deriving the difference εsb between this No. 1 or No. 2 and the actual rotational speed N. 31 is a speed control that uses the above-mentioned speed deviation εNb as an input, constantly makes this deviation εNb zero, and gives an active power command Pxr to the generator so as to ensure the stability of the speed control system of the hydraulic machine. Department.

f represents the frequency of the power system to which this generator is connected, fo represents its rated frequency, and Δf represents the deviation between f and fo.

24 is a speed change rate calculating section and a gain K11 time constant Tll
It is an incomplete differentiator circuit.

25 is a fixed band element, and 24 is an effective element that increases or decreases according to the overshoot when the speed change rate output from the speed change rate calculating section becomes higher than a predetermined value on the plus side or lower than a predetermined value on the minus side. Output power command Pχ2.

In addition, this PI3 acts in the direction of increasing the drive output (load from the power system's perspective) of the generator when j and Δj rise sharply, and on the other hand, when f suddenly falls, it acts in the direction of lowering the drive output and reduces the electric power. Acts to help stabilize the system.

The figure shows an alternative circuit for the part from Δf to PXz. In this case, it simply responds according to the amount of overshoot when the frequency deviation Δf itself exceeds a predetermined positive value or falls below a predetermined negative value. be.

FIG. 3 is a block diagram showing details of the 31 speed control section.

31b is a setter for the gain K11 during idle operation of the integral element 31e, and 31c is a setter for the gain KJ2 when the integral element 31e is switched from idle to power generation mode. Furthermore, for the reason stated in the explanation of the operation of the technical means of the present invention, KI2
is much larger than Kll. The integral element 31a is N-poor
b, that is, if even a slight deviation of N remains, the output of the generator is controlled so that the output Px1 continues to increase in the desired direction and N returns to No.

31a is a proportional element for improving the stability of this N control system. Note that 31f is an adder. 41 is a stationary band element that outputs no output as long as N remains within the variable speed band.When N attempts to overshoot beyond the upper or lower limit of the variable speed band, it is used to detect the amount of overshoot. is an element.

Reference numeral 42 denotes an Nlt repetition gain unit which generates a Pxs active power command correction signal in accordance with the amount of overshoot detected by the above-described stationary band element 41.

In other words, when N is about to go out of the variable speed band, the Nll feedback circuit consisting of 41 and 42 corrects the active power and returns N.
This is to prevent further rampage.

As is clear from FIG. 1, PΣ is a composite signal of the active power commands PXI, P)l, and the above-mentioned active power correction signal PX8.

The switch 32 is on the c side as shown in FIG. 1 during idling and switching from idling to power generation, and at the end of the switching, it is on the G side and turned OFF.

Furthermore, the switch 26 is in the C side, that is, in the ON state, only during idle operation, and immediately turns OFF when switching to power generation begins.

16 is a power detector that detects the actual power P of the generator 1.

Reference numeral 15 denotes an adder in which the deviation εP between PΣ and P is obtained. 17 APR (output control device) supports the direct current control unit 9 for the excitation current control device 37 according to this power deviation fp. 37 The excitation a current control device inputs the horizontal axis current command Id, the direct current command Iq, and the actual slip phase angle O8 similar to the known example shown in FIG. decide. Vo is a voltage setting value of the generator, and 33AQR is a reactive power controller, and the voltage setting value Vo is corrected by this output ΔVn.

(2) Σ is a composite signal of Vo and ΔVo, (2) is the actual voltage of the generator, and 35 is an adder that calculates the deviation fV between VΣ and V.

36AVR is a voltage control device that determines the horizontal axis current Ia according to this voltage deviation EV.

In the above, PΣ→15→εP→A P R−+I q
The control loop of →37→3→1→16→P→15 can be called an active power control system.

The stability and quick solubility of this active power system is 17APR (
It is set appropriately by the gain of the integral element and proportional element in the output control device).

On the other hand, the control loop of VΣ→35→tv→36→■6→37→3→1→voltage detector (not shown)→V→35 is a voltage control system, and the stability and quick solubility of this voltage control system are 36AVR (
It is appropriately set by the gain of the integral element and proportional element in the voltage control bag [).

Also N Of or Not→30→ff1Nb→31→PX
The control loop of I→27→the above active power control system→6→N→30 is a speed control system. The quick solubility and stability of this speed control system are determined by the proportional element 31a in the speed control section 31 and the
The desired level is set by adjusting the integral element gain setter 1b or 31c.

By the way, the key point in the present invention is to allow temporary follow-up fluctuations in the active power P when the fluctuations in the power system frequency f are large during idling operation.

Therefore, it is necessary to take care not to increase the proportional element 31a gain and the integral element gain 31b in the speed control section 31 excessively.

In other words, if the response speed of the speed control system is made too fast, the PX
This is because even if 2 occurs, it is quickly erased by the reverse fluctuation of PXI.

However, as a result of suppressing the response speed of the speed control system in this way, temporary fluctuations in the rotational speed N are unavoidable.

However, as mentioned above, since it is a variable speed machine, normal operation can be continued as long as N is within the variable speed band.

However, when N tries to jump out of the variable speed band, priority should be given to maintaining the variable speed band over the above f response function, and this is achieved by the aforementioned Nat return circuit, and the gain of the 42N kickback gain section. also needs to be set to a fairly high value.

Now, when the switching from idling mode to power generation mode is substantially completed and the guide vane opening is equal to or higher than the no-load opening and positive output can be produced from the water turbine, switch 32 to 0FFL and switch 28 to G side, and the full-scale operation begins. Enter power generation mode. Further, when a command to switch from the idle mode to the power generation mode is received, the switch 26 is switched to the G side, that is, turned OFF.
state. Then (after exhausting the compressed air in the runner chamber if necessary), the forced closing switch 8b is switched to release the forced closing command 5, and the guide vanes begin to open.

Incidentally, since the P#\l command at this point is a value greater than zero, it is natural that the optimum guide vane opening command Y& is greater than the no-load opening.

As explained in the operation section above, the power generation mode is initiated when N is near the lower limit of variable speed punt.

(In other words, N1 in Fig. 6 is equivalent to Nl.) Therefore, the operating points at this time are δ and δ', and the guide vane openings at this time are equivalent to 104 and 104', and below this, the figure 8 characteristic no longer exists. No abnormal phenomenon occurs during mode switching or even when full-scale power generation mode starts.

If the P command is increased from this state, the operating point will move according to the N and Y& commanded by the water turbine characteristic function generator, but generally as long as the P command is small, N& will remain near the lower limit of the variable band and only the guide vane opening will remain. It opens.

That is, the operating point in FIG. 6 moves from δ and δ' to ζ and ζ'.

Incidentally, FIG. 2 is a detailed diagram of the 11 rotational speed control computing unit shown in FIG. 1.

Reference numeral 21 denotes an f computing unit which contributes to the stabilization of the power system by issuing a P command correction signal ΔP in accordance with the fluctuation Δf of the power system frequency during the power generation mode.

Note that the gist of the present invention can also be applied to a variable speed power generation system in which a power converter is provided on the primary side of a generator.

〔Effect of the invention〕

According to the present invention, when switching from idling to power generation mode, a sudden jump phenomenon in the water turbine drive load caused by the figure-8 characteristic can be avoided, and smooth and reliable mode switching can be achieved.

Moreover, there is no need to disconnect from the line, and the switching can be completed in a short time.

Furthermore, we have finalized a concrete proposal for a mode switching system that is compatible with an ideal combination system in which active power control is performed in addition to reactive power control in idle mode, and output is controlled by guide vane control on the water turbine side in power generation mode.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2, 3, and 4 are partial detailed views of FIG. 1, and FIG. 5 is an explanatory diagram of a known biaxial excitation current control method. . FIG. 6 is a characteristic diagram of a pump water turbine, FIG. 7 is an explanatory diagram of a known variable speed power generation system, and FIG. 8 is an explanatory diagram of its operation. 17・APR133-AQR136・AVR.

Claims (1)

[Claims] 1. Regarding variable speed water turbine (or pump water turbine) equipment equipped with a water turbine (or pump water turbine) and a generator with a power converter capable of variable speed power generation operation in power generation mode, When switching from the idling mode in which the runner is idling by pressing down, to the power generation mode, the rotation speed is varied at least from the start of switching until the runner chamber is filled with water and the guide vane opening reaches approximately the no-load opening. A method of controlling the operation of a variable speed water turbine that maintains the transition near the lower limit of the band. 2. When switching from idle operation mode to power generation operation mode,
At the stage when the guide vane opening reaches approximately the no-load opening, the rotational speed control is switched from control by adjusting the drive output on the generator side to control by adjusting the guide vane opening on the water turbine side.
Method for controlling the operation of a variable speed water turbine as described in Section 1. 3. During idling operation, the target rotational speed is set near the center of the variable speed band, and when a command to switch to power generation mode is received, the target rotation speed is lowered to near the lower limit of the variable speed band and the transition to power generation mode is made.The first item The method for controlling the operation of the variable speed water turbine described above.