JPH0697879B2 - Initial loading circuit for steam turbine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a steam turbine that uses an electric speed governor, and more particularly, to a proper initial load amount in a load adjusting loop of the electric speed governor. The present invention relates to an initial load taking circuit for setting.

[Prior Art] Generally, when a turbine generator reaches a rated speed through a speed-up process by a turbine and is left alone for a while when it is included in the system, it is just included in the system due to fluctuations in the system frequency. There is a possibility that the turbine generator of (1) becomes reverse power (motoring) to cause a grid disconnection, and the operation of joining the grid again must be repeated. Such an operation of inserting a turbine generator into the system is an important operation that has an inherent risk of damaging the generator and the main transformer if it fails, and therefore unnecessary operation should be avoided as much as possible. I have to.

From this point of view, in an electric speed governor that conventionally controls the speed of a steam turbine, for example, an initial load-taking circuit as shown in FIG. 3 is provided to perform motoring immediately after the turbine generator is connected to the system. Is being prevented. That is, the third
The figure shows a load adjusting loop of an electric speed governor, reference numeral 10 is an output controller, 12 is a valve opening controller, 14 is an electric oil converter, 16 is a main servo, 18 is a control valve, 20 indicates a steam turbine, respectively. The output controller 10 is configured such that the output set value P _s and the output detected value P _d of the turbine generator are input, and the initial load amount set value set by the initial load take-up circuit 22 is input. It The valve opening detection value of the control valve 18 controlled by the main servo 16 is fed back to the valve opening setting value output from the output controller 10. Therefore, the initial load taking circuit 22
Includes an initial load amount setting device 24, a contact 26 which is linked to a main circuit breaker (not shown) for connecting the turbine generator to the system, and an output detector (not shown) of the turbine 20. ), And an auxiliary relay 30 that is energized by closing these contacts 26, 28. A normally open contact 30a that cooperates with this auxiliary relay 30 is provided as an output of the initial load amount setter 24. It consists of the structure provided in the line.

In the initial load take-up circuit 22 configured in this way, when the turbine generator reaches the rated speed and is inserted into the system by turning on the main circuit breaker, the contact 26 interlocking with the main circuit breaker is closed. The auxiliary relay 30 is activated. This makes contact 30
When a is closed, the load amount set by the initial load amount setting device 24 (usually about 2 to 5% of the full load) is added to the output set value P _s . In this case, since the output set value P _s immediately after joining the system is almost zero, the turbine generator has an initial load amount setter 24.
It will take the value set in. Therefore, the time transition of the generator load when using such an initial load taking circuit 22 is as shown in FIG.

Further, as a conventional control method for providing the initial load take-up circuit 22, as shown in FIG. 5, a counter 32 is provided on the output side of the output adjuster 10, and the valve opening adjuster 12 is provided through this counter 32.
Are known to be configured to generate the setpoint signal of. In this case, the initial load taking circuit 22 gives the initial load amount set value to the counter 32. For example, the contents of the counter 32 are rewritten so as to increase by 5% according to the initial load amount setting value. In this way, the initial load taking control of the turbine generator can be performed. The time course of the generator load at this time is as shown by the solid line in FIG.

[Problems to be solved by the invention]

However, in the control method using the above-mentioned conventional initial load-taking circuit, in the method shown in FIG. 3, as is clear from the characteristics shown in FIG. When the contact 28 (for example, the actual output ≧ 10% is the operating point) that operates in conjunction with the output detector is operating because it is strange and the generator load increases, the initial load from the initial load take-up circuit 22 Since the output of the volume setting value is turned off,
The generator load sharply decreases, and from that point, the generator load rises again based on the output set value P _s . Further, in the system shown in FIG. 5, there is no feedback of the turbine generator output with respect to the output set value P _s , and the system is an open loop control system. As a result of the change in the pressure, the load amount set value for initial load taking changes as shown by the broken line in FIG.

As described above, according to the control method using the conventional initial load taking circuit, the rise of the generator load is steep at the time of inserting the turbine generator into the system, and the initial load is increased due to the increase of the generator load. There is a problem that the generator load characteristics become unstable, such as the generator load fluctuating when the above is released, and the initial load amount setting value at the time of initial load taking changes due to fluctuations in steam pressure and the like.

Therefore, an object of the present invention is to provide a load adjustment loop of an electric speed governor for controlling the speed of a steam turbine, to soften the rise of the generator load characteristics at the time of initial load removal, and to perform load removal by a plant command from the initial load removal. It provides a steam turbine initial load take-up circuit that enables bumpless switching to the steam turbine and always achieves a constant load amount setting during initial load take-up without being affected by steam pressure fluctuations. To do.

[Means for solving problems]

The initial load-taking circuit of the steam turbine according to the present invention, when the turbine generator that has reached the rated speed is inserted into the system, the actual output of the turbine generator becomes a predetermined value in the output command value in the speed control system of the steam turbine. In the initial load take-up circuit of the steam turbine configured to add the required initial load amount set value until reaching, the initial load amount setter and the initial load amount set by this initial load amount setter Input the deviation between the value and the output detection value and integrate it to output the initial load amount command value, the output command value, and the initial load amount command value are input and the high value is selected and output. And a high-value selector that operates.

In the initial load-taking circuit, a comparator that detects that the output command value matches the initial load amount command value and outputs a predetermined signal, and the output signal of this comparator and the actual output of the turbine generator have a predetermined value. AND gate that inputs the signal output when it exceeds and outputs a predetermined signal, and input the closing signal of the main circuit breaker that operates when inserting the turbine generator into the system as a set signal and the AND A flip-flop which receives the output signal of the gate as a reset signal and controls the start and stop of the operation of the soft starter can be provided.

[Action]

According to the initial load-taking circuit of the steam turbine according to the present invention, when the turbine generator reaches the rated speed and merges it into the system, the output detection value is zero immediately after the merger. On the other hand, the initial load amount set value is input, the required integrated output is obtained, and an appropriate control signal to the speed control system based on the initial load amount set value can be output via the high value selector. In this case, when the actual output of the turbine generator exceeds a predetermined value, the integration operation of the soft starter is stopped based on this signal to stop the function of the initial load take-up circuit, and the speed is set only by the specified output value. The control of the control system can be smoothly achieved without causing motoring or the like.

〔Example〕

Next, an embodiment of an initial load taking circuit for a steam turbine according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a system diagram of an electric speed governor for speed control of a steam turbine showing an embodiment of an initial load take-up circuit according to the present invention. For convenience of explanation, the same components as those of the conventional device shown in FIGS. 3 and 5 will be designated by the same reference numerals. In FIG. 1, the electric speed governor of the present embodiment has a counter 32 connected to the output side of an output controller 10 that inputs the output set value P _s of the turbine generator and outputs the valve opening set value. An initial load taking circuit 34 is connected between the counter 32 and the valve opening degree adjuster 12.
Therefore, the initial load take-up circuit 34 of the present embodiment includes the initial load amount setter 36, the soft starter 38 having the proportional-integral operation characteristic (PI characteristic) or the integral operation characteristic (I characteristic), the upper limiter 40, and the high value. This high price selector with selector 42
The output of the counter 32 is input to 42, and the output of the high price selector 42 is connected to the valve opening adjuster 12. Therefore, the initial load taking circuit 34
Is the set value set by the initial load amount setter 36 (for example,
The deviation between the output value P _d of the turbine generator and the output detected value P _d of the turbine generator is calculated and input to the soft starter 38. This soft starter 38 starts the integration operation based on the output signal of the flip-flop 44 set by the closing command of the main circuit breaker when the turbine generator is connected to the system, and the high value selector via the upper limiter 40. Supplied to 42. However, since the output level of the output controller 10 is still low in the initial stage, the high value selector 42 selects the initial load amount command value and outputs it, and then the output command value of the output controller 10 gradually increases. When the initial load amount command value is exceeded, this output is selected by the high value selector 42 and supplied to the valve opening adjuster 12 as a valve opening set value. During this time, the switching of the output signal by the high price selector 42 is performed bumplessly. The upper limit limiter 40, for example, when the signal of the output detection value P _d is not output for some reason,
It has a function to limit the initial load setting value to a specified value so that it does not become excessive. In this way, when the detected output value of the turbine generator exceeds a predetermined value (for example, the actual output is 10% or more), the initial load taking circuit 34 becomes unnecessary from the load adjustment loop. Therefore, in the present embodiment, from the deviation between the initial load amount command value output from the upper limit limiter 40 and the output command value output from the counter 32, “1” is satisfied under the condition of initial load amount command value ≦ output command value. Comparator that outputs a signal
Provide 46. Further, an AND gate 48 for inputting the output of the comparator 46 and a determination signal as to whether or not the actual output of the turbine generator exceeds a predetermined value (for example, a “1” signal is output when the actual output ≧ 10%) Is provided and the output of the AND gate 48 is input to the flip-flop 44 to reset it. Therefore, by the operation of the comparator 46, the AND gate 48 and the flip-flop 44, the output of the soft starter 38 becomes zero, and the initial load taking circuit 34 stops its function.

Therefore, the generator load characteristics of the initial load take-up circuit 34 in this embodiment operating as described above are as shown in FIG. As is clear from the characteristics shown by the solid line in FIG. 2, according to the present invention, the rise of the generator load when the turbine generator is incorporated in the system is smoothed by the function of the soft starter 38, and the turbine generator The load characteristics of the generator when the actual output of the machine exceeds a specified value also becomes bumpless.

In this way, the valve opening set value output to the valve opening adjuster 12 is input as a deviation from the fed back valve opening detection value, and the required valve opening command value is output to output the electric oil. The main servo 16 is controlled via the converter 14 to operate the valve opening of the control valve 18, and the speed control of the steam turbine 20 is achieved.

〔The invention's effect〕

According to the present invention, as is not clear from the above-described embodiment, the output detection value of the turbine generator (which is zero immediately after being combined into the system) is input to the initial load amount setter as a signal for obtaining the deviation. However, by providing a soft starter having an integral operation characteristic and a high value selector that selects and outputs a high value from the initial load amount command value or the output command value, the generator load when the turbine generator is connected to the system is increased. It can soften the rise of characteristics, maintain a stable and constant initial load setting value, achieve smooth speed control of the steam turbine, and operate the turbine generator in parallel with the motor. It can be achieved stably and smoothly without producing a ring.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described initial load control of the steam turbine, and another prime mover (for example, a water turbine, a diesel engine,
It is also possible to apply to a power plant using a gas turbine or the like), and it is needless to say that various design changes can be made without departing from the spirit of the present invention.

[Brief description of drawings]

1 is a system diagram of an electric speed governor for controlling the speed of a steam turbine showing an embodiment of an initial load taking circuit for a steam turbine according to the present invention, and FIG. 2 is an initial load taking circuit shown in FIG. Fig. 3 is a generator load characteristic diagram of Fig. 3, Fig. 3 is a system diagram of a conventional electric speed governor equipped with an initial load-taking circuit, and Fig. 4 is Fig. 3
Generator load characteristic diagram by the initial load taking circuit shown in the figure,
FIG. 5 is a system diagram showing another example of the configuration of an electric speed governor provided with a conventional initial load take-up circuit, and FIG. 6 is a generator load characteristic diagram by the initial load take-up circuit shown in FIG. . 10 …… Output controller, 12 …… Valve opening controller 14 …… Electro-hydraulic converter, 16 …… Main servo 18 …… Control valve, 20 …… Turbine 22 …… Initial loading circuit 24 …… Initial load Amount setting device 26 …… Contact (main circuit breaker) 28 …… Contact (output detector) 30 …… Auxiliary relay, 30a …… Contact 32 …… Counter, 34 …… Initial load taking circuit 36 …… Initial load amount setting vessel 38 ...... soft starter, 40 ...... upper limiter 42 ...... high value selector 44 ...... flip-flop 46 ...... comparator, 48 ...... the AND gate P _s ...... output setting value, P _d ...... output detection value

Claims (2)

[Claims] 1. When a turbine generator that has reached a rated speed is inserted into a system, an initial load amount setting required for the output command value in the speed control system of the steam turbine until the actual output of the turbine generator reaches a predetermined value. In the initial load-taking circuit of a steam turbine configured to add a value to control the speed, the initial load amount setter and the deviation between the initial load amount set value set by this initial load amount setter and the output detection value. A soft starter that inputs and integrates this to output an initial load amount command value, and a high value selector that inputs the output command value and the initial load amount command value and selectively outputs the high value. Initial load-taking circuit for steam turbines. 2. An initial load take-up circuit according to claim 1, which detects that the output command value matches the initial load amount command value and outputs a predetermined signal, and an output of this comparator. AND gate that inputs the signal and the signal that is output when the actual output of the turbine generator exceeds a predetermined value and outputs the predetermined signal, and the main circuit breaker that operates when the turbine generator is inserted into the system. The initial load-taking circuit for the steam turbine, which is provided with a flip-flop for inputting the input signal as a set signal and the output signal of the AND gate as a reset signal and controlling the start and stop of the operation of the soft starter.