JP2889254B2 - Variable speed pumped storage power generation control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an AC-excited synchronous machine that enables variable-speed operation by variable-frequency AC excitation, and more particularly to an AC system in a variable-speed pumped-storage power generation system. The present invention relates to a variable speed pumped-storage power generation control device suitable as a load adjustment device for improving stability.

[Prior Art] In a pumped storage power generation system, variable speed operation is desirable from the viewpoint of load adjustment during pumped operation.

Therefore, instead of a synchronous machine, an AC-excited synchronous machine having a winding structure similar to a wound-type induction machine in which an armature winding is connected to an AC system and enabling variable-speed operation by variable-frequency AC excitation. There have been various proposals for technologies for realizing load adjustment during pumping operation using a power generator as a generator. Among them, a specific method for realizing precise load adjustment is disclosed in Japanese Patent Application No. As in the invention according to the application of Japanese Patent Application No. 60-9525, the driving device is controlled so that the deviation of the actual input with respect to the input command converges to zero, and the optimal guide vane opening is generated using the actual operation speed as an input. There is a method of controlling the opening and closing of the guide blade in accordance with a command from the container.

According to this method, it is possible to perform precise load adjustment during normal operation and operation under the highest efficiency, but on the other hand, in the start operation state from the stop state to the normal operation state. The control method is described in Japanese Patent Application No. 61-78133 and Japanese Patent Application No. 61-78133.
There are methods according to the inventions of -186828, and in any case, in these methods, the AC excitation synchronous machine performs control using the potential transfer of the AC power system as a reference signal.

When such a system is cut off from the AC power system, a reference signal for control is lost. However, there is also known an example in which a control method in such a case is mentioned.

Further, as a method of ensuring a sufficiently stable operation of the AC excitation synchronous machine even in the event of an abnormality in the AC power system, there is disclosed in, for example, JP-A-62-71496.

Here, a conventional example of such a pumped storage power generation system will be described below.

FIG. 7 shows an example of such a system. In the figure, reference numeral 5 denotes an AC excitation synchronous machine, and its armature winding 5a is connected to a breaker 2b for synchronization, a main transformer 3, and a system breaker 2a. Connected to the AC system 1.

Reference numeral 4 denotes a pump turbine, which is directly connected to the AC excitation synchronous machine 5 and functions as a water turbine during power generation and as a pump during pumping.

Reference numeral 6 denotes a frequency converter, which includes an exciting transformer 7 connected to the AC system 1 and a thyristor power converter 8 for converting the AC system frequency power stepped down by the exciting transformer 7 into low-frequency AC power. These are the AC excitation synchronous machine 5
Are provided independently for each phase of the exciting winding 5b.

9 is a phase detector, a resolver apparatus 12 for detecting a voltage transformer 10 for detecting the system voltage phase theta _v, the rotational phase theta _r expressed in electrical angle of the voltage phase calculator 11, AC-excited synchronous machine 5 , And a slip phase calculator 13.

Numeral 14 denotes an excitation current control device which adjusts the amplitude and phase of a three-phase AC current command rotating with the slip phase θ _s by two-axis current commands Iq and Id orthogonal to each other, The main switching element of the thyristor power converter 8 so that the line current matches the current command,
An automatic pulse phase shifter 16 converts the firing angle signal 15 to the thyristor
, And as a result, a roll pulse signal 17 is output from the automatic pulse phase shifter 16.

At this time, the current command signal adjusted by the exciting current control device 14 is disclosed in JP-B-52-7628 and JP-B-57-60645.
It may be provided by the method described in each public cover of the issue. That is, first, to control the active power output by adjusting the current command Iq with respect to the current component of the slip phase theta _s the same phase, while adjusting the current command Id with respect to the current component of the slip phase theta _s and quadrature The voltage is adjusted by the following.

The active power output and the voltage are taken out by an instrument current transformer 18 and an instrument transformer 10, respectively, converted into a predetermined DC signal by a measuring instrument 19, and then sent to an automatic active power control device 20 and an automatic voltage control. Input to the device 21.

On the other hand, the slip phase signal output from the slip phase calculator 13 is supplied to a frequency-voltage converter 22, and converted into a slip frequency signal f _s. The dead zone circuit 23 which generates a signal only when a frequency of the slip frequency signal f _s is out of the range of _{-f m ≦ f s ≦ + f} m
And an output correction command ΔP ₀ via a first-order lag element 24 that functions to reduce the output change, and is added to the output command P ₀ to the automatic active power control device 20. At this time, these commands ΔP ₀ and P ₀ are both
When the AC excitation synchronous machine 5 is operating as a motor during pumping, the direction of accelerating the motor is defined as positive.

[Problems to be Solved by the Invention] The prior art described above does not take into consideration the fact that when an abnormality occurs on the AC system side during the pumping operation, the armature frequency is likely to drop sharply. There was a problem in the stability of AC excitation operation by the device.

This problem will be described with reference to a conventional example shown in FIG. 7. If any abnormality occurs in the AC system 1, the system circuit breaker 2a
, The power supply to the AC excitation synchronous machine 5 is stopped, and as a result, the frequency of the armature 5a of the AC excitation synchronous machine 5 sharply drops due to the following three factors.

The vector diagram of the AC excitation synchronous machine 5 during the pumping operation is as shown in FIG. 8, and the vector of the induced voltage E is delayed in phase from the terminal voltage V.

On the other hand, when the input is cut off, the terminal voltage V becomes substantially equal to the induced voltage E. As a result, the voltage phase is delayed and the frequency is reduced.

During pumping operation, the AC excitation synchronous machine 5 as an electric motor
When the output of the active power control device 20 becomes zero,
As shown in FIG. 9, in the direction of increasing the output P, for example by changing the current command from Iq to Iq _1, this result, the exciting current command is transferred to I _ref1 from I _ref, further delaying the voltage phase, frequency Is changed in a direction to decrease.

During pumping operation, unlike the turbine operation, there is no function to adjust the rotation speed on the pump turbine side.

Therefore, when the input is cut off, the rotation speed drops sharply,
The voltage and frequency drop.

When the frequency suddenly decreases in this way, in order to keep the slip frequency within the set range, before the output correction command ΔP ₀ output via the dead zone circuit 23 functions and the correction operation works, the frequency is reduced. The AC excitation by the converter 6 is stopped, and as a result, in the related art, the stability of the AC excitation operation is deteriorated when the AC system is abnormal.

It is an object of the present invention to provide a variable-speed pumped-storage power generation control device capable of constantly maintaining a sufficiently stable operation state even when an AC system is abnormal during pumping operation and capable of continuous operation.

[Means for Solving the Problems] The above object is achieved by providing means for preventing the current command Iq from changing in the direction of instability when the AC system is abnormal.

Specifically, an armature winding connected to an AC power system,
An AC excitation synchronous machine having an excitation winding to which AC excitation power is supplied from the AC power system via a frequency conversion device for pump-turbine operation, and controlling the frequency conversion device to control the AC excitation synchronous machine. In the variable-speed pumped-storage power generator of the type that controls the active power, a command value switching means for forcibly fixing the command value for the active power to zero is provided to cope with the abnormality detection in the AC power system during the pumping operation. This is achieved by causing the command value switching means to perform a switching operation, and canceling the switching operation after a lapse of a time slightly longer than the high-speed reclosing time of the AC power system.

Further, in a system of a method in which the current command Iq is adjusted by the rotation speed control system, specifically, the armature winding connected to the AC power system and the AC excitation power from the AC power system via the frequency converter are generated. A variable-speed pumped-storage power generator of a type that includes an AC excitation synchronous machine having a supplied excitation winding for pump-turbine operation and controls the rotation speed of the AC excitation synchronous machine by controlling the frequency converter. A sample holding and replacing means for inputting a command value for the rotation speed is provided, and during pumping operation, the operation of the sample holding means is started in response to abnormality detection in the AC power system, and a high-speed re-start of the AC power system is performed. This is achieved by releasing the operation after a lapse of time slightly longer than the closing time.

[Operation] The active power command switching means switches the command to zero when an AC system abnormality occurs.

As a result, the current command Iq changes so as to mitigate the decrease in the armature frequency, and suppresses the decrease in the stability of the AC excitation operation by the frequency converter, whereby the abnormality in the AC system is restored by the high-speed reclosing function and the like. Continuous operation at times or the like can be enabled.

Further, the means for holding the output of the rotation speed control device holds the current command Iq even when the AC system is abnormal, so that it operates to mitigate the decrease in the armature frequency, and the stability of the AC excitation operation by the frequency conversion device is improved. Thus, it is possible to enable continuous operation when the abnormality in the AC system is restored by the high-speed reclosing function or the like.

Embodiment Hereinafter, a variable-speed pumped-storage power generation control device according to the present invention will be described in detail with reference to an illustrated embodiment.

FIG. 1 shows an embodiment of the present invention. The same reference numerals are given to the same parts as those in the conventional example described with reference to FIG. 7, and detailed description thereof is omitted, and different parts are mainly described. I do.

In FIG. 1, reference numeral 25 denotes a switching / timed circuit, and an input signal OP
And functions to control the selection switches 25a and 25b in accordance with.

The input signal OP to the switching / timed circuit 25 is a signal that is maintained at level 0 when the AC system is normal and switches to level 1 when an abnormality occurs.

The selection switches 25a and 25b are controlled by an output signal SW of the switching / timer circuit 25. When the signal SW is at level 0, the selection switches 25a and 25b are in the state shown in FIG. However, when the signal SW becomes level 1, the state is switched to the opposite state as shown in the figure,
As a result, the signal of level 0 is output as the output command OP by the adder 20.
Works like typing in a.

FIG. 2 is a timing chart showing the operation of the switching / timer circuit 25. As is clear from FIGS. 2 (a) and 2 (b), the switching / timer circuit 25 changes the input signal OP from level 0 to level 1 , The output signal SW also changes to level 1 in response to this, and thereafter, for a predetermined set time Td,
This level 1 is maintained. When the input signal OP has returned to level 0 after the lapse of the set time Td, the output signal SW also returns to level 0. At this time, when the input signal OP has reached level 1, It functions to keep the output signal SW at level 1 until the set time Td elapses.

Here, as the value of the set time Td, a time slightly longer than the high-speed reclosing time in the AC system is set.

Therefore, according to this embodiment, as apparent from FIG. 1, when an abnormality occurs in the AC system, the input signal OP changes from level 0 to level 1 in response to this, so that the selection switches 25a, 25b the switch to the opposite state shown, the output command P ₀ for automatic active power controller 20 is 0, the change in the unstable direction of the current command Iq would be effectively suppressed.

Then, as a result, in this embodiment, even when an abnormality occurs in the AC system, the rotation speed can be sufficiently suppressed from decreasing, so that the AC system immediately returns to the normal operation state immediately after the AC system recovers from the abnormality by the reclosing operation. It is possible to return and a stable operation state can be continued.

Next, FIG. 3 shows another embodiment of the present invention. In FIG. 1, reference numeral 26 denotes a comparator, and the other components are the same as those of the embodiment shown in FIG.

This comparator 26 is an active power output signal detected by the measuring instrument 19.
Comparing Pm with a predetermined set value P _1, the output signal changes from level 0 to level 1 when the former has come smaller than the latter
Works to generate OP. Here, the set value P _1,
The value is set to a value slightly smaller than the lower limit value of the pump input determined by the total head and the rotation speed range of the pump turbine 4.

According to the embodiment of FIG. 3, an external input signal OP
Irrespective of the AC power, it is possible to independently detect and respond to an abnormality in the AC system, suppress a decrease in rotation speed, and continue a stable operation state.

Further, according to this embodiment, when the input is cut off, the abnormality can be detected before the active power output signal Pm becomes 0, so that an operation with excellent responsiveness can be expected.

FIG. 4 shows still another embodiment of the present invention, in which 27 is an absolute value calculation circuit, 27a is an adder, and the other parts are the same as those in the embodiment of FIG.

Absolute value calculation circuit 27 is obtained from the adder 27a, and outputs the absolute value of the deviation between the effective power output signal Pm from the instrument 19 and the output command P _0, serve to enter it to the comparator 26 .

Therefore, in this embodiment, the output signal OP of the comparator 26 is
When the absolute value of the deviation of the active power output signal Pm and the output command P ₀ was greater summer than the predetermined set value P _2, a signal which changes from level 0 to level 1.

According to the embodiment shown in FIG. 4, even when the operation is performed such that the command value is transiently reduced to the lower limit value of the pump input or less for the purpose of stabilizing the AC system, a malfunction appears in the abnormality detection. And reliability can be further improved.

FIG. 5 is also an embodiment of the present invention.
Is a rotation speed control device, 29 is a rotation speed detector, 30 is a pump characteristic function generator, 31 is a sampler zero-order holding circuit, and the others are the same as those in the embodiment of FIG.

The rotation speed control device 28 is configured so that the deviation between the speed signal N from the rotation speed detector 29 and the speed command value N ₀ converges to 0.
It serves to adjust the current command value Ig _0.

Pump characteristic function generator 30 calculates the pump rotational speed corresponding to the output command P ₀ supplied from the outside and serves to output it as a rotational speed command N _0.

Sampler zero-order hold circuit 31, the current command value Ig ₀ at the time that the output signal SW from the switch-timing circuit 25 is changed from the level 0 to level 1 was sampled, and serves to hold it.

Accordance connexion, according to this embodiment, when the output signal SW for switching is changed to the level 1, the current command value Ig ₀ at this time is sampled and held, the selection switch is switched from 25a to 25b, this result current command Ig to the exciting current control device 14, the duration of the set time Td of the switching-timing circuit 25, to be fixed to the current command value Ig ₀ at abnormal time.

According to the embodiment of FIG. 5, even in a system using the rotation speed control device 28, as in the embodiment of FIG.
As in the case where the automatic active power control device 20 is used, stable operation can be continued when an abnormality occurs on the AC system side.

FIG. 6 shows still another embodiment of the present invention.
The comparator 26 converts the active power output signal Pm detected by the measuring instrument 19 into a predetermined set value P ₁ , as already described in the embodiment of FIG.
When the former becomes smaller than the latter, it functions to generate an output signal OP that changes from level 0 to level 1, and also at this time, the set value P ₁ The pump input is set to a value slightly smaller than the lower limit of the pump input determined by the head and the rotation speed range.

Therefore, according to the embodiment of FIG. 6, even in the system using the rotation speed control device 28, as in the case of using the automatic active power control value 20, as in the embodiment of FIG.
Stable continuation of operation when an abnormality occurs on the AC system side can be achieved.

[Effects of the Invention] According to the present invention, it is detected that an abnormality has occurred in the AC system, and thereby the current command to the exciting current control system is reduced for a predetermined set time in a direction to reduce the output or to a predetermined value. Since the voltage is maintained, even when an abnormality occurs in the AC system, an abrupt decrease in the motor frequency is suppressed, and there is an effect that stable operation can be continued from the time of occurrence of the abnormality to the time after recovery.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a variable speed pumped-storage power generation control device according to the present invention, FIG. 2 is a timing chart showing the operation of a switching / time limiting circuit, and FIGS. 6 is a block diagram showing one embodiment of the present invention, FIG. 7 is a block diagram showing a conventional example of a variable-speed pumped-storage power generation control device, FIG. 8 is a vector diagram during operation of the motor, and FIG.
The figure is a vector diagram showing a change in the current command when the input is cut off. 1 ... AC system, 3 ... Main transformer, 4 ... Pump turbine,
5 AC synchronous machine, 6 Frequency converter, 9
Phase detector, 14 ... exciting current control device, 20 ... automatic active power control device, 21 ... automatic voltage control device, 25 ... switching
Timed circuit, 25a, 25b …… Selection switch, 26 …… Comparator, 2
7 …… Absolute value calculation circuit, 28 …… Rotation speed control device, 29…
... Rotation speed detector, 30 ... Pump characteristic function generator, 31 ...
... Sampler zero-order holding circuit.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigehiro Ajikawa 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Hitachi, Ltd. Hitachi Plant Co., Ltd. (72) Norio Uchida 3-1-1, Sachimachi, Hitachi-shi, Ibaraki 1 Hitachi, Ltd. Hitachi Plant (72) Inventor Hiroto Nakagawa 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (56) References JP-A-57-196897 (JP, A) JP-A-63-218000 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02P 9/00-9/48

Claims (2)

(57) [Claims] An AC excitation synchronous machine having an armature winding connected to an AC power system and an excitation winding supplied with AC excitation power from the AC power system via a frequency converter is used for pump-turbine operation. In the variable speed pumped-storage power generator of the type controlling the active power of the AC excitation synchronous machine by controlling the frequency converter, a command value switching means for forcibly fixing a command value for the active power to zero During the pumping operation, the command value switching means is switched in response to the abnormality detection in the AC power system, and the switching operation is released after a lapse of a time slightly longer than the high-speed reclosing time of the AC power system. A variable-speed pumped-storage power generation control device characterized by being configured as described above. 2. An AC-excited synchronous machine having an armature winding connected to an AC power system and an excitation winding to which AC excitation power is supplied from the AC power system via a frequency converter for pump-turbine operation. A variable-speed pumping power generator of a type that controls the rotation speed of the AC excitation synchronous machine by controlling the frequency conversion device, further comprising: a sample holding / exchanging unit that receives a command value for the rotation speed as an input. During operation, the operation of the sample holding means is started in response to the abnormality detection in the AC power system, and the operation is canceled after a lapse of a time slightly longer than the high-speed re-closing time of the AC power system. A variable-speed pumped-storage power generation control device, characterized in that: