JPH0697030B2 - Variable speed turbine generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable speed turbine generator, and in particular, a rotary electric machine having a wire-wound rotor is used as a generator, and a rotary electric machine having this wire-wound rotor is used. The present invention relates to a variable-speed turbine generator that is suitable for enabling power generation operation near a synchronous speed with a minimum frequency converter capacity.

[Conventional technology]

As a variable speed turbine power generator of this type which has been generally adopted in the past, for example, one described in JP-A-59-72998 is known.

That is, as shown in the schematic view of FIG. 5, there is a rotating electric machine 1 having a wound rotor provided with primary and secondary windings, and the rotating electric machine having this wound rotor is directly connected to the rotor. The secondary winding 1b of the rotating electric machine 1 having a winding type rotor is driven to rotate by a rotating water turbine 2 and the rotational speed of the rotating electric machine having a winding type rotor is adjusted by an AC exciter 3 such as a cycloconverter. A variable speed operation is performed so that an AC exciting current adjusted to a predetermined phase is supplied in accordance with the above, and AC power having a frequency equal to that of the power system 4 is output from the primary winding 1a of the rotating electric machine 1 having a wound rotor. Is done.

Reference numeral 5 is a turbine characteristic function generator, which is a rotation speed signal N detected by the rotation speed detector 6 and a power generation output command given from the outside.
P ₀ and water level detection signal H are input, and optimum rotation speed command Nao and optimum guide valve opening command Yao for operating at maximum efficiency
To occur. Reference numeral 7 denotes an induction machine for slip phase detection, the rotor of which is directly connected to the rotary electric machine 1 having a wound rotor, and the primary winding 7a of which has a wound rotor 1
Of the secondary winding 7b, and is configured to output the slip phase signal Sp from the secondary winding 7b. The slip phase signal Sp and the optimum rotation speed command Nao are given to the cycloconverter 3 and, as described above, the phase of the AC exciting current supplied to the secondary winding 1b of the rotary electric machine 1 having the winding rotor. Etc. On the other hand, the optimum guide valve opening command Yao
Is given to the guide valve drive device 8, the opening of the guide valve 9 is controlled, and the turbine output PT is controlled.

[Problems to be solved by the invention]

Considering the case where the rotary electric machine 1 having a wound rotor is operated in the vicinity of the synchronous speed in such a power generator, the current is reversed because the cycle of the current polarity change of the cycl converter 3 is long. Since only one side of the cycloconverter 3 composed of parallel converters flows, the Joule heat energy received during this period becomes excessive and the cooling capacity is exceeded. As a result, the allowable output current capacity of the cycloconverter 3 is increased. Will be significantly reduced. Such a rotation speed range that is harsh for the cycloconverter 3 is called a cycloconverter output prohibition zone, and if it is designed so as not to pass through this range, the cycloconverter 3 becomes significantly large and expensive.

Therefore, based on the conventional technology, the cycloconverter output forbidden band is designed, and the operating range itself is narrowed by avoiding the power generation output range where the optimum rotation speed enters the forbidden band, thus achieving miniaturization of the cycloconverter capacity. Alternatively, a cyclone converter with a large capacity is used, and the entire power output range can be operated, that is, there is no forbidden band.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable speed turbine generator capable of providing the above-mentioned output forbidden band and adopting the minimum cycloconverter capacity.

[Means for solving problems]

The present invention relates to a generator having a primary winding connected to an electric power system, a secondary winding directly connected to a water turbine and rotating, and a secondary winding based on a generated power and a generated output command of the generator. In the variable speed turbine generator having an AC exciter for controlling the exciting current flowing through the rotor and a guide valve drive device for driving the guide valve of the water turbine according to the power generation output command, optimum rotation according to the power generation output command (Po). A turbine characteristic function generator (5) that outputs a speed command (Nao), and the optimum rotation speed command (Nao) enters within a cycloconverter output prohibited zone having a lower limit rotation speed (Nmin) and an upper limit rotation speed (Nmax). when,
A function generator (19) that corrects the optimum rotation speed command (Nao) to the outside of the cycloconverter output prohibited band, an actual rotation speed (N), and a rotation speed command (N) that is the output of the function generator (19). The guide valve drive device (8) controlled according to the deviation (ΔN) from the Na) and the actual rotation speed when the actual rotation speed (N) is within the cycloconverter output inhibition zone. (N) has a forbidden band kickback circuit (20) for outputting a forbidden band kickback signal (Pε) for promptly exiting the forbidden band, and has the power generation output command, the forbidden band kickback signal, and The AC exciter is controlled from the power generation output.

[Action]

Explaining with reference to FIG. 3, the figure shows the output-rotation characteristic in the case of a certain head H with the guide valve opening as a parameter, and in order to operate the water turbine at the highest efficiency point, the head H And the output P1 is given, the optimum rotation speed may be set to N1 of the point A. However, above all, it is necessary to surely avoid the cycloconverter forbidden zone (the range of rotation speeds Nmin to Nmax) near the synchronous speed, so slide to point A'where the decrease in turbine efficiency with respect to the difference in rotation speed is slight. So that the correction setting is made.

The kickback circuit means that when the actual rotation speed rises and tries to enter the forbidden band, the generator output command is suddenly increased near the lower limit of the forbidden band immediately before or immediately after entering the forbidden band. When the output (load on the turbine) is increased or the actual rotation speed decreases and the prohibition band is approaching the upper limit of the prohibition band, the power generation output command is corrected to be sharply reduced and applied to the generator. This is a circuit that reduces the output, which raises or lowers the actual rotation speed and kicks it back out of the rotation prohibition zone.

〔Example〕

The present invention will be described in detail based on the illustrated embodiments.

FIG. 1 is a block diagram of a power generator according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those in FIG. 5 indicate the same or corresponding parts, and the description thereof will be omitted. In the turbine characteristic function generator 5, as in the conventional case, the power generation output command P ₀ and the water level detection signal H
Is input, and the optimum rotation speed command Nao and the optimum guide valve opening command Yao are generated on the output side. Now, when the power generation output command P ₀ is raised and the optimum rotation speed command N 1 is accordingly entered into the prohibition zone where slippage is too severe for the cycloconverter, it is provided on the output side of the turbine characteristic function generator 5. The output of the hysteresis function generator 19 is corrected to a rotation speed command Na = Nmin equal to the rotation speed at the lower limit of the cycloconverter band and output as shown in FIG.

When the rotation speed command value Nao falls and enters the prohibited zone from above, the rotation speed command Nao is kept at Nmax until Nao falls to Nmin as shown in FIG.

The rotation speed command Na corrected in this way is applied to the rotation speed device 6
The actual rotation speed signal N detected in 1 is compared with the comparator 10, and the deviation ΔN (Na−N) is input to the calculator 11. The calculator 11 has a proportional element K1, an integral element K2 / S, and a derivative element K3.
It is composed of S and an adder 12, and outputs a correction signal ΔC so as to make this deviation zero as long as there is the deviation ΔN. The correction signal ΔC is added by the adder 13 to the optimum guide valve opening command Yao, and the output from the adder 13, that is, the corrected guide valve opening command (Yao + ΔC) is input to the guide valve drive device 8. The guide valve driving device 8 is composed of an adder 14 and an integrating element K4 / S, and its output is negatively fed back to the adder 14.

Further, the power generation output command P ₀ is combined with the output P ε of the forbidden band kickback circuit 20 described later in detail in the adder 21 to become P ₀ ′, which is input to the comparator 15 and the other input power generation. Compared with the actual power generation output signal PG detected by the output detector 16,
The deviation ΔP (P ₀ ′ -PG) is input to the power control device 17. The power control device 17 comprises a comparison element K6, an integration element K6 / S and an adder 18, the output of which is the cycloconverter 3
Entered in.

In the control device of this embodiment configured in this way, at the time point t ₀ in FIG. 2A, the power generation output command P ₀ is the optimum rotation speed.
When Nao is raised stepwise so as to enter the cycloconverter output forbidden band, the correction signal P ₀ ′ also changes stepwise, and the power generation of the rotating electric machine having the winding rotor, that is, the generator 1 having the winding rotor. As shown in FIG. 2 (g), the output signal PG rises following the change in the power generation output command P ₀ ′. However, since Nao exists in the forbidden band, the output Na of the history function generator 19 becomes Nmin. For the sake of simplicity, the forbidden band kickback circuit 20 will be described later, and the following description will be given assuming that the output Pε is zero for the time being.

Then, the integral element K8 / S included in the power control device 17, the cycloconverter 3, the generator 1 having the wound rotor,
Due to the negative feedback circuit composed of the power generation output detector 16 and the comparator 15, the deviation ΔP (P ₀ ′ −PG) gradually decreases, and PG = P ₀ ′ in a steady state. On the other hand, the opening responsiveness of the guide valve 9 to the guide valve opening command Y is slower than the responsiveness of the power generation output PG to the power generation output command P ₀ . Therefore, the turbine output PT becomes smaller than the power generation output PG,
As shown in FIG. 2 (f), the rotation speed N is the power generation output command.
After temporary deceleration due to a sudden change in P ₀ , time t _{1 in} FIG.
Then, the power generation output PG and the turbine output PT become almost equal, and the decrease of the rotation speed N stops. At the time point t ₁ , the deviation ΔN of the rotation speed is
Since (= Na−N) is positive and the correction signal ΔC output from the correction calculator 11 is positive, the guide valve opening command (Yao + ΔC) corrected by this correction signal ΔC is the optimum guide valve opening. It becomes larger than the command Yao, and eventually the turbine output PT is the power generation output PG
Will be greater than.

Therefore, the rotation speed N increases and approaches the rotation speed command Na, the correction signal ΔC also approaches zero, and finally the guide valve opening Y coincides with the optimum guide valve opening command Yao, and the rotation speed N is It becomes equal to the rotation speed command Na. That is, the integral element K2 / S included in the correction calculator 11, the adder 12, the adder 13, and
A negative feedback circuit composed of the guide valve driving device 8, the guide valve 9, the water turbine 2, the generator 1 having a wound rotor, the rotation speed detector 6 and the comparator 10 causes the deviation ΔN (= Na−
N) gradually decreases and becomes N = Na in a steady state. Further, in a steady state, the deviation ΔY (Yao−Y) = 0, that is, Yao = Y is the deviation ΔY (Yao−Y
Y) = 0, that is, Yao-Y.

(A) The optimum guide valve opening command Yao output from the water turbine characteristic function generator 5 naturally corresponds to the power generation output command P ₀ . (B) As mentioned above, PG during steady state =
It becomes P ₀ . (C) The inertia effect of all the rotating parts such as the runner of the water turbine 2 and the rotor of the generator 1 is determined by the turbine output PT and the power generation output PG.
It is accelerated or decelerated by the difference of
It can be regarded as a kind of integral element, and as described above, the correction calculator 11, the adder 13, the guide valve drive device 8, the guide valve 9, the water turbine 2, the generator 1, the rotation speed detector 6 and the comparator.
Since 10 forms the negative feedback circuit, PG = P _{0 in the} steady state. (D) The guide valve opening Y corresponds to the turbine output PT.

On the contrary, if the optimum rotation speed command Nao falls within the cycloconverter prohibition band when the power generation output command is lowered, the output of the history function generator 19 is the rotation speed equal to the cycloconverter output prohibition band upper limit rotation speed. Directive Na (= Nm
ax).

As described above, finally, the actual rotation speed N of the water turbine becomes equal to the rotation speed command Na corrected by the history function generator 19 and deviates from the forbidden band, but transiently the shaded area in FIG. 2 (f). As you can see, it temporarily enters the prohibited zone.

One of the objects of the present invention is to minimize this temporary entrapment and to allow a quick escape. Further, as shown in FIG. 8 (a), the power generation output command P ₀ increases, and along with this, the optimum rotation speed command Nao crosses from the bottom of the prohibited zone to the top, or as shown in FIG. 8 (b). Power generation output command P ₀ decreases, and the optimum rotation speed command Na
Rotation speed N when o crosses from the top to the bottom of the forbidden zone
The purpose is to shorten the time required to pass the band.

If the passage time can be shortened, the time for using one side of the anti-parallel converter of the cycloconverter can be shortened, so that the heat radiation amount due to the jail heat can be limited and the capacity of the cycloconverter can be reduced.

FIG. 7 is an explanatory diagram of a forbidden band kickback circuit which is a requirement of the present invention, and the optimum rotation speed command Nao is set so as to cross from the bottom to the top of the forbidden band as shown in FIG. Consider the case. The actual rotation speed N also rises as Nao rises, but when the rotation speed N reaches the lower limit of the forbidden band, that is, Nmin in FIG. 7, the output Pε of the forbidden band kickback circuit 20 is increased.

The maximum amount Pεmax of the output Pε of the kickback circuit 20 is set so that the speed command Nao crosses the forbidden band can be set as described later, but it is generally preferable to suppress it to about 20 to 30% of the rated output. .

As Pε increases, P ₀ ′ increases, resulting in generator output PG
Will increase. This means that as the load on the water turbine increases, the momentum of the increase in the rotation speed N is greatly broken near the lower limit Nmin of the prohibited zone, and the brake can be applied. Nevertheless, when the speed increase still does not stop and N reaches Nmin + ε, the output Pε of the forbidden band kickback element that has been output until now becomes zero.

Thus, PG also jumps to P _{0 in} steps. As a result, a positive deviation of Pεmax suddenly occurs between the combined output command P ₀ ′ = P ₀ + Pεmax up to now and the turbine output PT which is almost in balance, and the rotation speed N starts to rapidly increase and falls into the prohibited band at once. Cross and move to the new (above the band) optimum speed. As described above, the forbidden zone kickback circuit 20 controls the increase of the rotation speed N to stop between Nmin and Nmin + ε, and when the increase of N still does not stop, the N runs through the forbidden zone at once.

On the contrary, when the optimum rotation speed command Nao is set to traverse from the top to the bottom of the forbidden zone as shown in FIG. 8 (b), the rotation speed N is affected so as to stop falling between Nmax and Nmax-ε, Still N
As soon as Nmax-ε exceeds Nmax-ε, it accelerates and runs through the forbidden zone at once, and shifts to a new optimum rotation speed (below the forbidden zone).

The forbidden band kickback circuit 20 is composed of an N-Pε function generator as shown in FIG. 7 and a circuit for determining whether the rotational speed N is increasing or decreasing (for example, an incomplete differentiation circuit having a small time constant). Composed.

Incidentally, FIG. 7 shows an example of a forbidden band kickback circuit. When the rotational speed N is about to enter the forbidden band as described above, and when it cannot be pushed back at the entrance, the pushback is suddenly stopped to set the forbidden band. Anything that encourages quick passage is acceptable.

FIG. 6 shows an example of another speed command function generator which inputs the optimum rotation speed command Nao and outputs the rotation speed Na avoiding the forbidden band as an alternative to the history function generator 10 of FIG.

The output Na is N while the input optimum rotation speed command Nao is between Nmin and Nc.
Enter in min and set Nao to Nmax while Nao is between Nc and Nmax.

〔The invention's effect〕

As described above, according to the present invention, the history function generator 19 is provided so that the rotation speed of the generator 1 does not fall within the cycloconverter output prohibited band, and the rotation speed of the generator 1 is temporarily changed by the inertia of the water turbine 2. Even if it enters the converter output forbidden band, the forbidden band kickback circuit 20 is provided so as to minimize this entry and quickly move it to the outside of the cycloconverter output forbidden band, or to allow it to pass quickly. Since the current does not flow only to one side of the anti-parallel converter configuring the above, excessive Joule heat is not generated, and the output current capacity of the cycloconverter 3 can be reduced, so that an economical design can be achieved. There is.

[Brief description of drawings]

FIG. 1 is a block diagram of a variable speed turbine generator according to an embodiment of the present invention, FIGS. 2 (a) to 2 (g) are waveform diagrams of signals in respective parts of the generator, and FIG. The figure which shows the relationship between the turbine output and the optimum rotation speed and the guide valve opening degree, FIG. 4 is a figure which shows the input-output relationship of a hysteresis function generator, FIG. 5 is an example of the conventional variable speed turbine generator. 6 is a block diagram showing a speed command function generator used in place of the history function generator shown in FIG. 4, FIG. 7 is an explanatory view of the action of a forbidden band kickback element, and FIG. 8 is a forbidden band. This is an example in which the optimum rotation speed command is set and moved across. 1 ... A rotating electric machine (or generator) having a wound rotor,
2 ... water turbine, 3 ... cycloconverter, 4 ... electric power system, 5 ... turbine characteristic function generator, 6 ... rotation speed detector, 7 ... slip phase detection induction machine, 8 ... guide valve drive device , 9 ... Guide valve, 10 ... Comparator, 11 ... Computing unit, 13
...... Adder, 15 …… Comparator, 16 …… Generation output detector, 17
...... Power control device, 19 …… Historical function generator, 20 …… Forbidden band kickback circuit, 21 …… Adder, P ₀ …… Modified power generation output command.

Front Page Continuation (72) Inventor Akira Bando 3-1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Akio Ito 5-2-1 Omikacho, Hitachi City, Ibaraki Prefecture Stock company Hitachi Omika Plant (72) Inventor Shigeaki Hayashi 3-22 Nakanoshima 3-chome, Kita-ku, Osaka-shi, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Eiji Haraguchi 3-chome Nakanoshima 3-chome, Kita-ku, Osaka No.22 in Kansai Electric Power Co., Inc.

Claims (1)

[Claims] 1. A primary winding (1) connected to a power system (4)
a) and the secondary winding (1) that is directly connected to the water turbine (2) and rotates.
a generator (1) provided with b), and an alternating current excitation device for controlling the exciting current flowing from the generator (1) to the secondary winding (1b) from the generated power (PG) and the generated output command (Po). (3)
And a variable speed water turbine power generator having a guide valve drive device (8) for driving a guide valve (9) of the water turbine (2) according to the power generation output command (Po). Optimal rotation speed command (Na
o) output turbine characteristic function generator (5), when the optimum rotation speed command (Nao) falls within the cycloconverter output inhibition zone having the lower limit rotation speed (Nmin) and the upper limit rotation speed (Nmax), The optimum rotation speed command (Nao)
A function generator (19) that corrects and sets the outside of the cycloconverter output prohibited band, and a deviation (ΔN) between the actual rotation speed (N) and the rotation speed command (Na) that is the output of the function generator (19). And the guide valve drive device (8) controlled according to (1)), and when the actual rotation speed (N) is included in the cycloconverter output inhibition zone, the actual rotation speed (N) is changed from the inhibition zone. A forbidden band kickback circuit (20) that outputs a forbidden band kickback signal (Pε) for prompt escape is provided, and the power generation output command (Po) and the forbidden band kickback signal (P) are provided.
ε), and the AC exciter (3) is controlled from the power generation output (PG), a variable speed turbine generator.