JPH0822160B2 - Power plant load adjusting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to load control of a power generation plant, and particularly when a thermal power generation plant is automatically operated by a power supply station command, an excessive amount of life such that the service life of the plant equipment is deteriorated. The present invention relates to a load adjusting device for a thermal power plant that is suitable for following a load to a power supply station command while suppressing the load fluctuation.

[Conventional technology]

With the construction of the nuclear power plant that bears the base load, recently, the thermal power plant is also required to adjust the power to absorb the supply and demand balance of the power system. Excellent DSS (Daily Start-Up and Shut-dow
n) Firepower is being built.

Conventionally, a thermal power plant is an ELD (economic load distribution) from a power supply station, which is a signal instructed to each power plant by economically optimal load distribution calculation for many power plants.
The command signal cycle is usually as long as 15 minutes or more) signal and AF
C (frequency control: a regulated load command signal for keeping the frequency of the electric power system constant, and the command signal cycle is usually relatively short at 2 to 15 minutes) enables automatic operation. Since these ELD and AFC signals are made with economic efficiency as an index from the viewpoint of power system operation, plant characteristics (load response, etc.) are limited on the ELD and AFC signal receiving side (plant side). I am considering.

Fig. 4 shows an example of conventional technology, but the ELD from the power supply station
The signal 1 passes through the ELD control on / off switch 3 that switches between control of the output target value and the manual setting device 7, and the target output pattern signal is output by the subtractor 4, the load change rate up / down limiter 5, and the integrator 6. 106 is made. In addition, the AFC signal 2 from the power supply station is switched between the limit by the manual setting device 15 and the automatic setting of the AFC width (load change width) by the switching device 16, and is limited by the load change width upper / lower limit controller 11. Similarly to the ELD signal, the subtractor 12, the load change rate upper / lower limit limiter 13, and the integrator 14 generate an adjustment load pattern signal 114 for system frequency adjustment, which is added by the adder 10
Is added to the target output pattern signal 106, and the turbine output is controlled by the generator output command 101.

Here, the load change rate limit for the ELD signal is set by the setter 9.
However, in the case of automatic operation, the load change rate setting automatic / manual switch 8 limits the load change rate by the signal from the function generator 31. This function generator 31
The F ₁ (X) characteristic of is a function of the generator output as shown in FIG.

On the other hand, the load change width and load change rate with respect to the AFC signal are limited by the switchers 16 and 18 and the function generator 32 and
Automatically set by 33 signals.

The F ₂ (X) and F ₃ (X) characteristics of the function generators 32 and 33 are also the fifth
As shown, it is a function of the generator output.

When the AFC control is switched, a zero value 17 is set in the load change rate upper / lower limit limiter 13.

In this way, it is possible to respond to the load demand by the ELD signal and the AFC signal from the power feed station within the range of the load change rate and the load change width that the plant allows.

However, the load change rate limiting function mentioned here is effective for a relatively slow load change (a large load change of 2 to 4 times a day), but a high frequency load due to a power supply command. It was never considered change.

Note that, as a device related to this kind of device, for example,
Thermal power nuclear power generation, Vol. 27, No. 8, pp. 21-29, JP-A-59-231604 and the like.

[Problems to be solved by the invention]

The above conventional technology responds to a load change request from the power supply station,
It is limited by the allowable load change rate and the allowable load change width set uniquely as a function of the generator output. This limit value is the allowable value for one load change, and a large load change is There is no problem as long as it is about 2 to 4 times, but there is a big problem not only shortening the service life of the plant material equipment but also fatigue failure of the equipment in response to a demand for frequent load changes.

FIG. 6 shows a load operation pattern when the same load change rate and load change width are limited. The load pattern (B) has a large number of load changes, and this is because the load change pattern is large. It is easy to understand that it will affect the number of years.

It is an object of the present invention to provide a load adjusting device for a power plant that follows a load station command at a high load change rate while maintaining the service life of the plant equipment even with a high frequency load change request.

[Means for solving problems]

The above purpose focuses on the fact that load changes change with time demands, and determines the allowable load change rate and allowable load change range using the load increase / decrease rate per hour (called load change rate) as an index. This is achieved by limiting load change demands from the office.

[Action]

If the load variation rate is calculated as the ratio of the integrated value of the load increase / decrease times in the output operation to the output operation time integrated value of the power plant, the load variation rate always shows the average value in the operation. On the other hand, since the plant equipment service life depends largely on the number of load changes, by adjusting the allowable load change rate according to the averaged load change rate,
It is possible to perform load following control that manages the useful life of plant equipment.

〔Example〕

An embodiment of the present invention will be described above with reference to FIGS.

FIG. 1 shows a control circuit that receives an ELD signal 1 and an AFC signal 2, which are load request commands from a power supply station, and creates a generator output command value in a power plant side device. The ELD signal 1 switches the output target value to the operation by the manual setting device 7 and the switching device 3
This signal is selected by the subtractor 4, the load change rate upper / lower limit limiter 5, and the integrator 6, and the target output pattern signal 10
Become 6.

Also, the AFC signal 2 from the power supply station is the AFC width (load change width)
The limiter 11 selects the limit by the manual setting device 15 and the limiter by the automatic setting by the switching device 16, and the limiter 11 limits the load change range. The upper and lower limiter 13 and the integrator 14 serve as an adjustment load pattern signal 114 for system frequency adjustment, which is added to the target output pattern signal 106 by the adder 10 to generate a generator output command signal. It becomes 101. The signal 101 is matched with the generator actual output 102 by the subtractor 19, and the governor is adjusted by the deviation signal 103.

Here, the load change rate limit for the ELD signal 1 can be manually set from the load change rate setter 9 through the switcher 8.
Although it is automatically limited by the function generator (F ₁ (X)) 31, the limiting circuit 21 obtains a limiting coefficient for the signal of the function generator 31 according to the load fluctuation rate, and this is multiplied by the multiplier 23. Therefore, the load change rate can be limited in consideration of the load change rate. This ELD load fluctuation protection circuit 91 is a technology that has never existed before.

In addition, the load change width for AFC signal 2 is calculated by the function generator (F
₂ (X)) 32, and the load change rate is automatically set by the function generator (F ₃ (X)) 33, but the signal of these function generators is limited by the AFC load fluctuation rate. By obtaining the coefficient by the limiting circuit 22 and multiplying the frame deviation through the switch 26, the load change rate limit or the load change width limit can be performed in consideration of the AFC load change rate. The switch 26 allows selection of whether the load change is prioritized or the load change width is prioritized, and may be fixed without installing the switch. This AFC load fluctuation protection circuit 92 is a technology that has never existed before.

FIG. 2 shows the function of the limiting circuit 21. This circuit includes a counter 41 for counting the number of signal changes of the target output pattern signal 106, an integrator 42 for integrating the operating time during output operation, and a count number ( The divider 43 that divides a) by the time integrated value (b) and the result of this division The function generator 44 calculates a limiting coefficient (c) for limiting the load change rate.

The counter 41 counts the frequency of load change by a method such as integrating 1 each time the load change rate (differential value) of the signal 106 changes from negative to positive. Further, the output signal c of the function generator 44 is made dimensionless so that a change in plant operation can be easily dealt with.

It should be noted that the counter 41 does not count a very small load change that does not affect the life of the device.

FIG. 3 shows the function of the limiting circuit 22, which is almost the same as the limiting circuit 21 in FIG. 2, but because it is a protection circuit against the AFC signal, the counter 45 is for adjustment for system frequency adjustment. The number of signal changes of the load pattern signal 114 is counted. Also, the integrator 46 integrates only the operating time of AFC control. The circuit configuration is a counter 45, an integrator 46, and a divider 4 that divides the count number (a ') by the time integrated value (b').
3, and the division result From the relation generator 47 for determining the coefficient (c ') for limiting the load change.

The counting method of the counter 45 and the characteristic of the function generator 47 are the same as those of the limiting circuit 21.

According to the above-described embodiment, the number of load fluctuations in operating time units is obtained by a long-term integrated value (continuously integrated during plant operation), so that it works effectively as an index for managing the service life of plant equipment. For example, a case of a power plant which has a service life of 30 years (operating time of 240,000 hours) and allows a load change frequency of 436,000 during this period will be described with reference to FIGS.

In Fig. 7, load fluctuation rate 1.8 times / HR (= 436,000 / 24
When the plant is operating with a target value of 0,000),
If the actual load change rate is the value A at the current point, it is possible to continue operation at a high load change rate while the plant equipment service life of 30 years is maintained, although it is very close to the restricted area. If the actual load fluctuation rate is a value of B at the present point, there is a margin for the useful life of the equipment, so high frequency load change operation is possible with a high load change rate until the load fluctuation rate averages 1.8 times / HR. Become.

On the other hand, if the high-frequency load change operation is forced in the past and the actual load change rate at the present time is the value of c, it is in the area where the load change is limited, so the number of load change times is suppressed and the load change rate averages 1.8. The load change rate (or load change width) is limited until the number of times / HR is reached.

Note that the fact that the number of load changes can be suppressed by applying a load change rate limit to a high frequency load change request is as shown in FIG.

〔The invention's effect〕

According to the present invention, it becomes possible to perform load operation while maintaining the useful life of plant equipment according to the load fluctuation rate, and it is possible to safely and automatically operate the power plant even in response to a high-frequency load change request from the power supply station. .

[Brief description of drawings]

FIG. 1 is a control block diagram of a thermal power plant having a protection circuit against the load fluctuation rate (the number of load changes per operating time) according to the present invention, and FIGS. 2 and 3 explain the function of the protection circuit of FIG. Functional diagram, FIG. 4 is a control block diagram of a conventional thermal power plant, FIG. 5 is a diagram showing a specific example of the function generator shown in FIG. 4, and FIG. 6 is a diagram showing a load pattern of the thermal power plant. , 7 and 8 are explanatory views showing the operation of the function. 101 …… Generator output command signal, 102 …… Generator output value, 10
3 …… Turbine governor control signal, 106 …… Target output pattern signal, 114 …… System frequency adjustment load pattern signal.

Claims (1)

[Claims] [Claim 1] Load request command (ELD signal, AFC
Signal) and power plant load setting command are switched by the switch.
A circuit that determines the generator target output of the power plant based on these command signals, and an allowable load change rate and an allowable load change range for plant start / stop and large load changes to prevent excessive load change operation in response to the required load command. In a plant output control device consisting of a load change limiting circuit for limiting the command signal with the above, the allowable load change rate and the allowable load change range are determined by the magnitude of the load change rate represented by the number of load changes in operating time units. A load adjusting device for a power plant, which is provided with a load fluctuation protection circuit that enables a high-frequency load change operation by limiting the load.