JP2523520B2 - Control device for variable speed turbine generator - Google Patents

Description

The present invention relates to a control device for a variable speed turbine generator using an induction machine and a secondary excitation control device connected to the secondary side of the induction machine.

[Conventional technology]

As a control device for a variable speed turbine generator using a conventional induction machine and a secondary excitation control device connected to the secondary side thereof, for example, Japanese Patent Application Laid-Open No. 52-46428, Japanese Patent Application No. 57-182920, and Japanese Patent Application Laid-Open No. 55
−56499 etc. have been proposed.

Generally, a common problem of variable speed turbine generators is whether to control the rotation speed by controlling the turbine output and the generator output. Specifically, the speed deviation signal obtained by comparing the optimum rotation speed command value N _a and the rotational speed detection value N for calculating from the signals including power generation output command signal P ₀ from at least the outer shows a water wheel operating conditions (N _a -N) The issue is how to use the turbine to control the output of the turbine and generator. Because, when adjusting the rotation speed by mechanically connecting the turbine and the generator, the fluid kinetic energy of the water channel system is smaller than the rotational kinetic energy of the mechanical system, and the loss of the generator is almost negligible. This is because the difference between the output of the turbine and the output of the generator is almost the same as the increase and decrease of the rotational kinetic energy. Here, the power generation output command P ₀ from the outside is the power generation calculated from the measurement signals such as voltage, current, frequency, phase and rotation speed of the equipment that constitutes the variable speed power generator such as the water turbine, the generator and the frequency converter. It means a power generation output command other than the output command. Specifically, it means a power generation output command from the outside of the power generation device such as a central power supply command station.

Japanese Unexamined Patent Publication No. Sho 55-given as a method for connecting a primary side of a wire wound induction machine to an AC system and providing a frequency converter between the secondary side and the AC system in a control device for a variable speed turbine generator.
In No. 56499, the speed of the driving medium (flow rate for a turbine),
We have proposed a configuration that uses three types of measurement signals for rotation speed and generator stator output for generator output control and turbine output control.
However, there is no specific proposal on how to control the generator output and the turbine output to control the rotation speed. Further, there is no specific proposal as to how the generator output is made to respond to the power generation output command P ₀ from the outside.

Japanese Patent Application Laid-Open No. 52-46428 and Japanese Patent Application No. 57-182920, which are cited as proposals for a control device for a variable speed turbine generator of this type, describe a control method for controlling a generator output using a rotation speed deviation signal. is suggesting. FIG. 5 shows an example of the configuration of the control device for these variable speed turbine generators. In FIG. 5, reference numeral 1 denotes an induction machine, which is rotationally driven by a water turbine 2 directly connected to its rotor, and a secondary excitation control device 3 having a frequency converter on a secondary winding 1b of the induction machine 1. An AC excitation current adjusted to a predetermined phase according to the rotation speed of the induction machine 1 is supplied, and AC power of the same frequency as the AC system 4 is output from the primary winding 1a of the induction machine 1. Variable speed operation is performed. Reference numeral 5 denotes a water wheel characteristic function generator, which inputs an externally generated power output command P ₀ and a water level detection signal H to generate an optimum rotation speed command N _a and an optimum guide valve opening command Y _a for operating at maximum efficiency. appear. A slip phase detector 7 detects a slip phase S _P equal to the difference between the voltage phase of the AC system 4 and the secondary side rotation phase of the induction machine expressed in electrical angle. 8 generates an induction generator output command PG by comparing the rotational speed detection signal N between the optimum rotational speed command N _a from the water turbine characteristic function generator 5 in the induction generator output command device from the rotational speed detector 6. It slips phase signal S _P output and the induction generator output command PG the slips phase detector 7 is inputted to the secondary excitation control device 3, active power detector of the induction machine 1 detected by the 9 output detection signal P is induction machine The AC exciting current supplied to the secondary winding 1b of the induction machine 1 is controlled so as to be equal to the output command PG. Specifically, a control method proposed in Japanese Patent Publication No. 57-60645 can be applied. 10 adjusts the opening degree of the guide valve 11 in accordance with the optimum guide valve opening command Y _a from hydraulic turbine characteristic function generator 5 in guiding valve driving apparatus, for controlling the water turbine output PT. In such a control device, when the power generation output command P ₀ is changed as shown in FIG. 8 (a) in order to increase the power generation output P stepwise, the power generation output command P ₀ is increased stepwise. As a result, the optimum rotation speed command N _a and the optimum guide valve opening command Y _a also rise in steps as shown in FIGS. 8 (b) and 8 (c), and the guide valve
The opening Y of 11 is controlled by the guide valve driving device 10 so as to sequentially match the guide valve opening command Y _a as shown in FIG. 8 (d).
Along with the change in the opening Y of the guide valve, the turbine output PT also changes as shown in FIG. 8 (e) and becomes a value corresponding to the power generation output command P ₀ . Meanwhile, in order to match the rotational speed N of the induction machine 1 in FIG. 8 (f) to be raised as shown optimum rotating speed command N _a rotation system of the kinetic energy of the generator only justify the rise Need to be increased. This kinetic energy increase can only be compensated by increasing the turbine output PT or decreasing the power generation output P. However waterwheel output PT to the Yotsute waterwheel output PT to opening Y are determined for guiding valve 11 that changes according to the optimum guide valve opening command Y _a as is urgently not increase. For this reason, the kinetic energy increase is supplied to the rotating system by reducing the power generation output P, and as shown in FIG. Problems occur in the operation of the grid. In order to prevent this transient decrease in the power generation output P, the optimum rotation speed command N _a of the water turbine characteristic function generator 5 is input to the device for suppressing the sudden change of the signal such as the first-order lag element inside the induction machine output command device 8. Then, a method of comparing the output of this device and the rotation speed detection signal N from the rotation speed detector 6 to generate the induction machine output command PG can be considered. By this method, a part of the increase in the turbine output PT can be supplied to the increase in the rotational kinetic energy, and the rest can be distributed to the increase in the output P of the induction machine 1. However, even with this method, the output P of the induction machine 1 cannot be increased faster than the increase of the turbine output PT, and there is a drawback that the response speed of the power generator is suppressed by the response of the guide valve drive device 10. This problem also occurs when trying to lower the power generation output command P ₀ stepwise. These problems are basically caused by controlling only the output of the induction machine 1 to control the rotation speed N.

In addition, basically, the delay of the output response of the turbine to the output response of the generator is transiently absorbed by the kinetic energy of the rotating part, and the output of the generator is directly controlled according to the power output command. Sho-60-210004 has been proposed.
This control method will be described with reference to FIG. In this figure, the same parts as those in FIG. 5 are designated by the same reference numerals, and only different parts will be described.

Reference numeral 15 is a rotation speed command calculator P ₀
And an optimum rotation speed command N _a is generated according to the water level signal H from the outside. Water level signal H in the case of a power generator with little fluctuation in water level
Without inputting the power generation output command P ₀ only, the optimum speed command N _a
May occur. 16 generates the guide valve opening command Y _a by comparing the rotational speed signal N detected by the optimum rotation command N _a in the rotational speed controller speed detector 6. FIG. 7 shows an embodiment of the rotation speed control device 16. Reference numeral 17 is a comparator for detecting the rotational speed deviation ΔN. This rotation speed deviation ΔN is input to 18 comparison elements K1 and 19 integration elements (K2 / S), and these outputs are input to the guide valve drive device 10 as the guide valve opening command Y _a by the adder 20. . On the other hand, external power output command P ₀
Is input to the rotational speed command calculator 15 and is also input as a power generation output command to the secondary excitation control device 3.

In the control device of the present embodiment configured as described above, the power generation output command P ₀ is made stepwise as shown in FIG. 9A in order to increase the power generation output P stepwise at the time t ₀ . When raised, the power generation output P of the induction machine 1 becomes 9th.
As shown in the figure (g), it rises following the change in the power generation output P ₀ . On the other hand, the guide valve opening command Y _a changes as shown in FIG. 9 (b) due to the output change of the proportional element 18 because the final rotation speed command N _a rises stepwise as shown in FIG. 9 (c). It changes into a step shape. However, the response of the opening degree Y of the guide valve 11 is slower than the response speed of the induction machine output P to the above-described power generation output command P ₀ . Therefore, the turbine output rather than the induction machine output P
The PT becomes smaller and the rotation speed N is temporarily decelerated after the sudden change of the power generation output command P ₀ , and at the time point t ₁ , the power generation output P and the turbine output PT become equal and the rotation speed N becomes the minimum. Time point
Since the speed deviation ΔN is positive at t ₁ , the guide valve opening command Y _a continues to rise by the integral element 19. Guide valve opening Y continues to increase, the rotational speed N tying t ₂ equals the optimum rotational speed command N _a, the guide valve opening Y _a becomes maximum. Thereafter, the guide valve opening Y and the rotational speed N is the rotational speed N while attenuating vibration to settle the optimum rotational speed command N _a. Power output P and the hydraulic turbine output PT at t ₃ and t ₅ in FIG. 9 are equal, the rotational speed at the time point t ₄ N and optimum rotational speed command N _a are equal.

The power output P to follow faster than the response of the guide valve 11 to changes in the power generation output command P ₀ From the above, it is possible to settle the rotational speed N to the optimum rotating speed N _a. This first using a rotary kinetic energy in order to follow the power output P with respect to changes in the power generation output command P _0, the optimum rotational speed command N _a the output P of the induction machine 1 while keeping the power output command P ₀ The rotational kinetic energy required to adjust the rotation speed N is
It was realized by controlling and supplying 11.

[Problems to be solved by the invention]

In the above-mentioned conventional example, no consideration is given to switching to the variable speed pumped storage power generator from the system, that is, switching to so-called no-load excited excitation at the time of load or disconnection, and self-excited operation of the secondary excitation control device is not considered. There was a problem that it was difficult to shift to certain no-load excitation operation or independent operation in the station where power was supplied only to auxiliary equipment in the power plant. These problems are problems that do not exist in conventional synchronous machines that do not control torque by excitation control.

FIG. 10 shows the operation when the system is loaded or disconnected by the method shown in FIG. When the load is applied or disconnected at t ₀ in the figure, the power generation output P becomes zero. For this reason, the rotation speed N starts to rapidly increase, and the guide valve 11 is closed by the rotation speed control device 16, but the rotation speed N
Continues to rise until t ₁ . On the other hand, since the output command P ₀ remains fixed, the current command value output by the current control system in the secondary excitation control device 3 raises the output. For example, if a limiter is provided for the current command value, the current command value will be constant at time t ₂ , but the output command of the current control system will be the secondary excitation control device 3 because the deviation between the current command value and the actual current is large. The output voltage exceeded the maximum value. Therefore, normal operation cannot be performed, and for example, the secondary excitation control device 3
There was a problem that an overcurrent flowed to the.

On the other hand, when the speed control is performed by the secondary excitation control device 3 as shown in FIG. 5, the speed control is actually performed in a state in which the generator output P cannot be controlled, so that the increase of the rotation speed N can be suppressed. There was a problem that I could not.

An object of the present invention is to provide a control device for a variable-speed turbine generator for stably shifting to no-load excited excitation operation or independent operation in a station.

[Means for solving problems]

The above object is achieved by providing a command value switching device that switches the output command to the system to zero by a signal that detects that the variable speed turbine generator has been disconnected from the system.

[Action]

Since the output of the variable-speed turbine generator must be zero when the command value switching device is loaded or disconnected from the system, it shifts to a stable equilibrium state with no-load excitation and independent operation in the plant. Can be made.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In this figure, the same parts as those in FIG. 6 are designated by the same reference numerals, and only the parts different from those in FIG. 6 will be described here.

21 is a command value switching device, which is a signal SW that detects load and disconnection
Thus, the connection is switched between the contact A and the contact B. signal
The SW is normally connected to the contact A of the switching device 21 at level 0. During this time, the rotation speed command calculator
The command signal to 15 and the secondary excitation control device 3 becomes a command signal P ₀ from the outside. On the other hand, when the signal SW becomes level 1 upon detection of load or disconnection, the contact B of the switching device 21 is connected. At this time, the command signal P ₀ becomes 0.

FIG. 2 shows the operation when the load or the load is cut off in this configuration.
When the load is applied or disconnected at t ₀ in the figure, the power generation output P becomes zero. First
As in Fig. 10, the rotation speed N begins to rise sharply. When load or disconnection is detected at time t ₃ , the command value switching device 21 operates and the output command P ₀ becomes zero. Along with this, the secondary excitation device 3
The current command value output by the internal current control circuit of was changing in the direction to increase the output, but this time it is changing to the direction in which the output is zero, and is settled to the steady operation at time t ₄ ,
It is possible to stably shift to no-load excitation or independent operation in the plant. According to this embodiment, the rotation speed during the unloaded excitation operation becomes the rotation speed command value when the output command P ₀ is zero. This value is the minimum rotation speed determined by the specifications of the secondary excitation control device 3, and is lower than the value during normal operation. This has the effect of reducing the mechanical loss of the induction machine 1 and reducing the amount of water in the water turbine 2.

FIG. 3 shows another embodiment of the present invention. Reference numeral 22 denotes a command value switching device, and in the present embodiment, in addition to the active power output command P ₀ , the reactive power command Q ₀ is also switched.
That is, in this embodiment, the secondary excitation control device 23 is configured to control the detection values of the active power output P and the reactive power output Q to the grid from the detector 24 to be equal to the command values PG and QG. ing. When the signal SW becomes level 1, the command value switching device 22 switches from the contacts A ₁ and A ₂ to the contacts B ₁ and B ₂ , respectively,
Both commands P ₀ and Q ₀ are based on 0.

According to this embodiment, even when the reactive power control is performed by the variable speed turbine generator, it is possible to stably shift to the no-load excited excitation operation or the in-house independent operation.

FIG. 4 shows another embodiment, in which the electromagnetic coil 25 is excited when the rate of change (dN / dt) of the detection value N of the rotation speed detector 6 is equal to or greater than the set value. Further, the electromagnetic coil 27 is excited when the time limit switch 26 is closed, the manual return switch 28 is closed, and the signal SW changes from level 0 to level 1. Generally, in order to detect loading or disconnection, the operating state of the system or the disconnector of the system to which the power plant is connected is transmitted to the power plant. Utilizing the fact that the speed increases sharply when disconnected, this is detected by the rotation speed detector 6
Since there is no signal from the outside, there is an effect that the load or the disconnection signal SW is obtained. Of course, a logical sum of an external signal and the output of the embodiment shown in FIG. 3 can be used.

〔The invention's effect〕

As described above, the present invention is provided with a command value switching device, and by this command value switching device, when the variable speed turbine generator is disconnected from the system, the output command to the system is switched to zero. Thus, it is possible to stably shift to the no-load excitation operation and the independent operation in the office.

[Brief description of drawings]

FIG. 1 is a block diagram of a control device for a variable speed turbine generator according to an embodiment of the present invention, and FIG. 2 is an operation characteristic diagram of FIG.
3 and 4 are a block diagram and a circuit diagram of a main part of a controller of a variable speed turbine generator according to another embodiment of the present invention, and FIGS. 5, 6 and 7 are conventional controls. Block diagrams of the apparatus, FIGS. 8, 9, and 10 are operational characteristic diagrams in the above conventional example. 1 ... induction machine, 2 ... water turbine, 3 ... secondary excitation control device,
4 ... AC system, 6 ... Rotation speed detector, 10 ... Guide valve drive device, 11 ... Guide valve, 15 ... Rotation speed command calculator,
16 …… Rotation speed control device, 21 …… Command selector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigehiro Ayukawa 3-1-1, Saiwaicho, Hitachi City Hitachi Factory, Hitachi Ltd. (72) Akio Ito 5-2-1 Omikacho, Hitachi Stock Company Hitachi Omika Plant (72) Inventor Eiji Haraguchi 3-3-22 Nakanoshima, Kita-ku, Osaka City Kansai Electric Power Co., Inc. (72) Hiroto Nakagawa 3-3-22 Nakanoshima, Kita-ku, Osaka City Kansai (56) References JP-A-58-148626 (JP, A) JP-A-57-199499 (JP, A) JP-A-59-132724 (JP, A) JP-A-58-218900 (JP , A)

Claims (2)

(57) [Claims] 1. An induction machine whose primary side is connected to an AC system,
AC power of the same frequency as the AC system is connected to the induction machine in response to an output command signal from the outside that is connected between the primary side and the secondary side of the induction machine and includes at least an active power output command to the system. A secondary excitation control device to be generated, a water turbine that rotationally drives the induction machine, a guide valve that adjusts the amount of water supplied to the water turbine, and the opening of the guide valve is controlled according to a guide valve opening command signal. Guide valve driving device, a rotation speed detector for detecting the rotation speed of the induction machine, and an output speed command signal indicating the turbine operating condition including at least an active power output command signal from the outside to input an optimum rotation speed command. A rotation speed command calculator for calculating the rotation speed control device for comparing the optimum rotation speed command signal with the rotation speed detection signal of the rotation speed detector to control the guide valve opening command signal to the guide valve drive device. Consists of In a control device for a variable speed turbine generator, an output command to the AC system including at least the active power output command is set to zero by a signal for detecting that the variable speed turbine generator is disconnected from the AC system. A control device for a variable-speed turbine generator, which is provided with a command value switching device for switching to. 2. The signal according to claim 1, wherein the rate of increase of the rotation speed detection signal is a signal for detecting that the variable speed turbine generator is disconnected or disconnected from the AC system. A control device for a variable-speed turbine generator, which is obtained by using a switching device that operates when a set value is exceeded.