JPH03215197A - Plant load controller - Google Patents

Abstract

PURPOSE:To cancell unbalance between governor-free operation and frequency- bias signal by setting signal due to turbine inlet steam pressure and a load limiter follow-up width, to be of the upper limit setting value of the frequency- bias signal. CONSTITUTION:Upper limit signal 44 corresponding with frequency-bias upper- limit signal is created by a circuit means consisting of a multiplier 45 for multiplying the same load limiter follow-up width signal 39 as the signal of input provided to a load limiter, by turbine inlet steam pressure setting signal 46, and a proportional device 47. In other words, from the turbine inlet steam pressure and the load limiter follow-up width of a turbine controlling line, the upper limit setting value of the frequency-bias signal 44 for objective load command is contrived to be found. Accordingly, the frequency-bias signal 44 is to be limited to an upper limit value in consideration of load limiter working at the time of governor-free operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a plant load control device equipped with boiler turbine cooperative control and a governor-free function for a thermal power plant, which drives a generator by a steam turbine such as a nuclear power plant. It can also be applied to power plants.

An example of a conventional plant load control device using the dependent flux technique is the one shown in FIG. 2, for example.

In the block diagram of FIG. 2, the plant load control device obtains a boiler input command 20 from a target load command 1, a system frequency deviation signal 2, and a turbine inlet steam pressure l5, and further obtains a generator output signal 2l and a load limiter follow-up width signal. 39 to obtain a turbine steam valve opening command signal 37, and a governor free signal 31 is generated from the turbine rotation speed signal 26 and turbine rotation speed setting signal 28 to control the turbine steam valve. It consists of a control system that has a Gahana-free function for inputting input to the system.

In the boiler control system, the frequency high ass signal 12 is converted from the system frequency deviation signal 2 to the signal 4 generated by the function generator 3, from the target load command 1 to the frequency bias upper limit signal 6 generated by the function generator 5. It is created by multiplying the upper and lower limits using the lower limit signal 8, the low value selector 9, and the high value selector 11.

The power generation command signal 14 is created by adding the target load command 1 and the frequency high-ass signal 12 in an adder 13, and is further added in the adder 19 with an output signal l8 of a controller l7 that controls the turbine inlet steam pressure l5. Boiler input command 2
It becomes 0.

The power generation command signal 14 is also compared with the generator output signal 21 in a subtracter 22 and becomes a turbine master signal 25 by the controller 24 .

The turbine master signal 2l is added by an adder 32 to a Gahana free signal 31 which is proportional to the turbine rotational speed deviation, and becomes a turbine steam valve opening signal 33. Next, this turbine steam valve opening degree signal 33 passes through a low value selector 34 and becomes a turbine steam valve opening degree command 37 by a control inlet 36 . The low value selector 34 is activated by the load limiter setting signal 43, because if the turbine steam valve suddenly opens, the steam pressure will decrease and the main engine and auxiliary equipment will be adversely affected. , an upper limit is set for the turbine steam valve opening signal 33.

The load limiter setting signal 43 is outputted by an adder 40 to the first steam valve opening signal 38 and the load limiter follow-up width signal 39.
This is the signal obtained by adding the above signals and multiplying the rate by the speed limiter 42. That is, when the turbine steam valve opening signal 38 changes to the load limiter follow-up width signal 39 or more at a speed higher than the rate set by the speed limiter 42, the signal from the load limiter side or the turbine steam valve opening command signal 35 changes. selected.

Further, in such a case, the load limiter stops the follow-up operation and is fixed at the time when the signal on the load limiter side is selected, so the turbine steam valve will not open any further.

The governor free signal 31 includes the turbine rotation speed signal 26 and the turbine rotation speed setting signal 2 from the turbine rotation speed setting device 29.
8 using a subtracter 27 and applying the deviation to a proportional device 30.

SUMMARY OF THE INVENTION The Gahana-free function changes the opening degree of the turbine steam valve by an amount proportional to the turbine rotation speed deviation created using the subtractor 27 from the turbine rotation speed signal 26 and the turbine rotation speed setting signal 28. It is something that makes you

Turbine rotation speed signal 26 or turbine rotation speed setting signal 28
When the turbine steam valve opening signal 33 suddenly decreases compared to , the turbine steam valve opening signal 33 rapidly increases due to the governor free function, but the upper limit is applied by the load limiter setting signal 43, and at that point, the low limiter setting signal 43 is fixed.

The low limiter setting signal 43 is generated by adding the turbine steam valve opening signal 38 and the load limiter follow-up width signal 39 using an adder 40 and applying the result to a speed limiter 42 .

Therefore, the maximum amount of change in generator output due to governor free when the turbine rotation speed suddenly decreases (when the system frequency decreases) is determined by the turbine inlet steam pressure and the load limiter follow-up width.

On the other hand, the power generation command signal l4 is the target load command 1 plus the frequency high-ass signal 12, and the frequency high-ass signal 12 indicates the power generation amount with the governor free at the rated pressure by the function generator 3 in the relationship of Δf. The upper limit signal 6 and the lower limit signal 8 are set within a range that is permissible for the boiler.

In the conventional control system, the frequency high-ass signal l2 is such that the turbine steam valve opening command 37 is limited by the load limiter.
The upper limit signal 6 is supposed to increase even when the Kahana free operation is not working, and conversely, if the upper limit signal 6 is set low even when the turbine steam valve or rotor limiter is not applied, the frequency bias signal 12 increases. is limited before the required amount is obtained, and in either case, an imbalance occurs between the governor free and the frequency bias, and the boiler input command 20 and the Tahin steam valve, which should always work in coordination, There is a problem in that an imbalance occurs between the opening command 37 and the system frequency control, which is the purpose of governor-free, as a result.

Means for Solving the Problems The amount of change in generator output due to the governor free function is approximately proportional to the product of the amount of change ΔG in the turbine steam valve opening and the turbine inlet steam pressure Pt. In the case of a system disturbance such as a sudden drop in system frequency, the turbine steam valve operates in the opening direction due to the governor free function, but the sudden opening action limits the follow-up width of the low limiter. Therefore, the maximum opening change amount of the evening steam valve due to the governor free function ΔG MAX
is equal to the low limiter width.

Therefore, the present invention uses the plant load control device to obtain a signal corresponding to the maximum generator output change due to the governor free function from the turbine inlet steam pressure and the load limiter tracking width of the turbine control system, and calculates this signal at the frequency corresponding to the target load command. It has circuit means for setting the upper limit setting value of the bias signal.

Effect According to the above means, by setting the signal based on the turbine inlet steam pressure and the load limiter tracking width as the upper limit setting value of the frequency bias signal, the generator output signal added as a bias by an amount equivalent to the governor free portion is used. , the boiler and turbine will be controlled in a coordinated manner.

EXAMPLE Hereinafter, a preferred example of the present invention will be described in detail with reference to FIG. In FIG. 1, the same parts as those shown in FIG. 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

According to the device of the present invention, the upper limit signal 44 corresponding to the frequency hias upper limit signal 6 is sent to the multiplier 45 which multiplies the same low limiter tracking width signal 39 input to the load limiter by the turbine inlet steam pressure setting 46. and a proportional device 47.

The proportional gain of the proportional device 47 is, for example, MWo/(Po-Go
)And it is sufficient. Here, M'wo, Po, and Go are the generator output, turbine inlet pressure, and turbine steam valve opening, respectively, at the rated plant.

As a result, the frequency bias upper limit signal 44 becomes Pset/
PoXΔG/GO×Mivo (1). Ps
et is the turbine inlet steam pressure setting, and ΔG is the load limiter follow-up width.

Equation (1) represents the amount of change in the generator output when the turbine steam valve opening changes by the low limiter follow-up width ΔG when the turbine inlet steam pressure setting Pset changes, and the load limiter follow-up width ΔG suddenly changes due to the system frequency. It is equal to the amount of change in the opening degree of the turbine steam valve due to the governor free function when the governor free function decreases.

By setting the value of equation (1) as the upper limit setting value of the frequency high-ass signal 12, it is possible to create a power generation command signal 14 that adds a frequency high-ass amount that is balanced with the Gahana-free function, and enables cooperative control of the boiler and turbine. Or it works effectively.

That is, the frequency high ass signal 12 and the Gahana free signal 3
It becomes possible to control the controller 24 without pulling back or raising the controller 24 due to an imbalance with 1.

Effects of the Invention According to the present invention, the upper limit setting value of the frequency bias signal for the target load command is determined from the turbine inlet steam pressure and the load limiter follow-up width of the turbine control system, so that the frequency bias signal is adjusted to the load limiter during free operation. The frequency is now limited to an upper limit value that takes into account the limiter operation, and the imbalance between Gahana-free and frequency bias is eliminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a control system of a plant load control device according to the present invention, and FIG. 2 is a diagram showing a conventional example. 1. Target load command, 2. System frequency deviation signal, 3.
5...Function generator, 6...Frequency bias upper limit signal, 8
...Frequency bias lower limit signal, 9...Low value selector, 1l
・・High value selector, 12・・Frequency bias signal, 14・
・Power generation command signal, 15...Turbine inlet steam pressure, 1
7. Controller, 20. Boiler inlet command, 21.
- Generator output signal, 24... Controller, 25... Turbine mask signal, 26... Turbine rotation speed signal, 29
...Turbine speed setting device, 30...Proportional device, 31...
Governor free signal, 33...Turbine steam valve opening signal,
34...Low value selector, 36...Controller, 37...
Turbine steam valve opening command, 39...Low limiter follow-up width signal, 42...Speed limiter, 43...Load limiter setting signal, 44...Frequency bias upper limit signal, 45...
Multiplier, 46...Turbine inlet steam pressure setting, 47...
Proportional instrument.

Claims (1)

[Claims] A circuit means for determining a signal corresponding to the maximum generator output change amount due to the governor free function from the turbine inlet steam pressure and the low limiter follow-up width of the turbine control system, and setting this as the upper limit setting value of the frequency bias signal with respect to the target load command. Plant load control device with.