JPH0480619B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a frequency control method for a shaft generator that can be driven by two drive sources simultaneously, and particularly relates to a frequency control method for a shaft generator that can be driven from one drive source by sharing the load. When trying to drive a shaft generator that is currently operating from another system, the droop characteristic curve of the drive source of the other system is automatically shifted in parallel to prevent frequency fluctuations in the shaft generator. Concerning what has been done.

[Prior Art] In the case of a shaft generator that can be driven simultaneously from two drive sources, before being driven simultaneously by the two systems,
First, one system is driven and begins operation, and then the remaining systems are added and may be driven simultaneously. In this case, when the shaft generator is driven by one system, the speed is controlled by the speed governor of the drive source, but when it is driven by two systems simultaneously, the frequency control is unified. , switch the speed governor of one drive source that has been working until now to another mode (pressure regulation mode for turbine engines), stop speed control, and switch to the speed governor of the drive source of the additional system instead. Therefore, frequency control is performed.

Therefore, when the two systems are driven simultaneously, the frequency of the shaft generator is determined according to the droop characteristic of the drive source of the additional system.

[Problems to be Solved by the Invention] However, the shaft generator that is driven by one system is already in a state where it has a load, and when it is switched from one system to two system drive in that state,
Since the speed droop of the shaft generator is controlled by the droop of the additional system, there is a problem in that the frequency suddenly drops depending on the load, making the operation unstable.

[Objective of the invention] The present invention solves the above problems and provides a frequency control method for a shaft generator that allows stable operation without causing frequency fluctuations even when switching from single-system drive to dual-system drive. That is.

[Summary of the Invention] In order to achieve the above object, the present invention is based on the knowledge that if the droop characteristic curve of the drive source of the additional system is equal to the droop characteristic curve of the drive source of the preceding system, no frequency fluctuation will occur. , while the shaft generator is being driven by one drive source 2 and is being simultaneously driven by the other drive source 4, the frequency f of the other drive source 4 is changed to the shaft generator being driven by one drive source 2 and being in operation. 1, the other drive source 4 is adjusted according to the deviation between the detection frequency of the other drive source 4 and the set frequency F that asymptotically approaches the reference frequency Fa.
The Dhruv characteristic curve is configured to be translated in advance.

[Example] An example of the present invention will be described below based on FIGS. 1 to 3.

As shown in Fig. 1, 1 is a synchronous generator as a shaft generator, which uses part of the power of a turbine engine 2 and a main engine 3 to maintain constant shaft rotation even if the rotational speed of the main engine 3 changes. It is designed to be driven simultaneously from two drive sources including a rotation control device 4 that outputs a number.
The shaft generator 1 and the rotation control device 4 are connected via a clutch 5, and the shaft generator 1 can be driven by the turbine engine 2 alone. In some cases, this shaft generator 1 is connected to a bus bar to which another generator 6 is connected, so that it can be operated in parallel with the other generator 6.

Incidentally, the deviation between the detected frequency of the output of the rotation control device 4 and the set frequency F is input to the speed governor 7 of the rotation control device 4, and the speed governor 7 adjusts the output of the rotation control device 4 according to this deviation. The frequency is controlled to a set frequency F.

The set frequency F is generated by a set frequency generation circuit shown in FIG. This set frequency generation circuit is composed of a correction frequency generation circuit 10, a reference frequency generation circuit 11, a comparison circuit 12, and a variable frequency generation circuit 13.

The correction frequency generating circuit 10 is composed of a linear function circuit of the correction command signal, and is designed to generate a correction frequency ΔHz whose value changes monotonically while the command signal is present. That is, while there is an INC speed increase command, the correction frequency ΔHz increases sequentially, and while there is a DEC deceleration command, it sequentially decreases. This INC directive and
There are two types of DEC commands: an external command signal A that is generated manually or by an AFR (automatic frequency stabilizer), and an internal command signal B that is automatically generated.

The comparator 12 has a function of generating this internal command signal B, and compares the reference frequency Fa of the reference frequency generation circuit 11 with the set frequency F to find that Fa>F.
It is configured to output an INC command when Fa<F, and a DEC command when Fa<F. That is, the INC command or DEC command is output until the reference frequency Fa and the set frequency F match. These command signals are generated by a two-system drive switching signal C, which is generated when the shaft generator 1 is switched from independent drive by the turbine engine 2 to composite drive in which the rotation control device 4 is also driven. Input to the circuit 10 is prohibited.

The fluctuating frequency generation circuit 13 operates when switching to combined operation.
It consists of a memory circuit that stores in advance the fluctuating frequency that occurs in the rotation control device 4 depending on the load, and outputs the fluctuating frequency y that corresponds to the load signal D.

The set frequency F, which is the output of the set frequency generation circuit, is the sum of the reference frequency Fa and the correction frequency ΔHz of the correction frequency generation circuit 10 minus the fluctuation frequency y of the fluctuation frequency generation circuit 13, that is, F. It is obtained from =Fa+ΔHz−y.

Now, in the above configuration, it is assumed that the shaft generator 1 is independently driven by the turbine engine 2 and is operated in parallel with another generator 6 with a load of x%. From this state, the rotation control device 4
When attempting to drive the shaft generator 1 in a combined manner by adding the drive from the oscilloscope, the power to the set frequency generating circuit shown in FIG. 1 is turned on before turning on the clutch 5.
Then, since ΔHz=0 when the power is turned on, the set frequency F of the speed governor 7 of the rotation control device 4 becomes F=Fa−y. That is, the set frequency F of the rotation control device 4 initially starts from a point lower than the reference frequency Fa (60 Hz in the embodiment) by the fluctuation frequency y. This is because the frequency of the currently rotating rotation control device 4 originally has a certain fluctuation range.
This is because it is not possible to know where the operating point is, and therefore proper control is performed by starting from a point outside the above fluctuation range. In this sense, it is not necessarily necessary to determine the variable frequency y corresponding to the x load, but in this embodiment, y is selected for convenience.

Since the set frequency becomes F=Fa-y in this way, an INC command is issued from the comparator circuit 12 that compares and determines this with the reference frequency Fa, and this INC command is input to the correction frequency generation circuit 10. While the INC command is input, the correction frequency ΔHz from the correction frequency generation circuit 10 is as follows: ΔHz = ΔHz (t ₀ ) = ΔHz (t ₀ ) + ΔHz (t ₁ ) = ΔHz (t ₀ ) + ΔHz (t ₁ ) ...+ΔHz(tn). In other words, the correction frequency ΔHz increases not suddenly but sequentially. The reason why the correction frequency ΔHz is increased sequentially in this way is to prevent hunting and resonance that occur when the correction frequency increases rapidly.

Therefore, the frequency of the rotation control device 4 is F=Fa
- It gradually increases from y. And ΔHz=y
When this happens, F=Fa, the INC command disappears, and the set frequency F becomes F=Fa. As a result, the set frequency F of the rotation speed control device 4 to the speed governor 7 is fixed to its final value, which is the reference frequency Fa, and therefore, the output frequency of the rotation speed control device 4 becomes Fa. That is, as shown in FIG. 3, the droop characteristic curve A of the rotation speed control device 4 automatically moves parallel to the droop characteristic curve B of the independently driven shaft generator 1 operating in parallel at x% load. come to a consensus.

The effect of finally fixing the frequency of the rotation speed control device 4 to the reference frequency Fa works in exactly the same way even in the case of a DEC command that occurs when Fa<F.

When the droop characteristic curve A of the rotation control device 4 matches that of the shaft generator 1, the clutch 5 is turned on to switch the shaft generator 1 to composite drive.

Note that when entering composite drive, the internal command signal from the comparator circuit 12 is prohibited, and instead, the internal command signal from the outside is used.
The set frequency can be changed by INC/DEC command.

In this way, when the shaft generator 1 is being driven independently at x% load, when switching to combined drive using the conventional droop characteristic curve A, the shaft generator 1 is controlled by this curve A, so that the shaft generator 1 has a sudden increase of yHz. However, in this embodiment, the droop characteristic curve of the rotation control device 4 is automatically moved in parallel by changing the set frequency F until just before switching to compound drive, so the set frequency F always maintains the reference frequency Fa. can.
Therefore, even when switching from single drive to combined drive, the shaft generator 1 does not cause frequency fluctuations and can operate stably.

Immediately after switching the composite drive, the droop is activated according to the B curve, and thereafter the B curve can be moved in parallel in the vertical direction by an external command.

[Effects of the Invention] In short, according to the present invention, the droop characteristic curve of the additional drive source is automatically translated in parallel until immediately before switching to simultaneous drive, so that it matches the droop characteristic curve of the preceding drive source. As a result, the set frequency of the additional drive source can always be maintained at the reference frequency, and even when switching to simultaneous drive, no frequency fluctuation occurs, and the shaft generator can always be operated stably.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a power generation system for carrying out the method of the present invention, Fig. 2 is a block diagram showing a preferred embodiment of a set frequency generation circuit similarly used in the method of the present invention, and Fig. 3 is a diagram of the present invention. It is a load/frequency characteristic diagram obtained by the method. In the figure, 1 is a shaft generator, 2 is a turbine engine that is one drive source, 4 is a rotation control device that is the other drive source, is a detection frequency, and F is a set frequency.

Claims (1)

[Claims] 1 When a shaft generator that can be shaft-driven by two drive sources simultaneously is driven by one drive source and simultaneously driven by the other drive source, the setting frequency of the other drive source is set to one drive source. A frequency control method for a shaft generator, characterized in that the droop characteristic curve of the other drive source is moved in parallel in advance so as to match the reference frequency of the shaft generator being driven by the shaft generator.