JPH01155003A - Electro hydraulic type control device for turbine - Google Patents

Abstract

PURPOSE:To prevent generation of motoring by providing a switching means changed over by the opening or closing of a generator breaker and a lower limit restrainer for giving the minimum limit to a regulation valve opening signal at the time of closing the generator breaker. CONSTITUTION:In the state that a generator 6 is connected to an electric power system 8, namely, in the state that a generator breaker 7 is closed, a switch 9 is connected to a lower limit restrainer 10. And also, immediately after the generator 6 is connected to the electric power system 8, the set value of a speed load setting device 1a is made a speed set value corresponding to the initial load value (several % of a rated output). A converter 1c converts a speed deflection signal corresponding to the initial load which is output of an adder 1b, into the opening of a regulation valve 4 corresponding to the initial load so as to apply its output to the lower limit restrainer 10. The lower limit value of the lower limit restrainer 10 is set in a range from not less than opening for keeping the unload rated speed +alpha to less than the initial load. Therefore, the regulation valve 4 is opened only to the extent corresponding to the initial load without such a condition that the regulating valve opening signal corresponding to the initial load from the converter 1c is restrained to the lower limit by the lower limit restrainer 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a turbine electro-hydraulic control device for a turbine generator in a thermal power plant.

(Prior Art) Generally, output control and speed control of a turbine generator are performed by controlling the amount of steam flowing into the turbine by adjusting the ratio of a regulating valve based on an output signal from a speed governor.

The conventional control of a turbine using a speed governor will be explained with reference to FIG. The basic operation of the turbine electro-hydraulic control device is to set a speed setting value obtained by converting the load setting value to speed using the speed load setter 1a in the speed governor 1, and to set the speed of the turbine 5 detected by the speed detector 2. An adder 1b calculates a speed deviation signal between the converter 1c and a converter 1c. The converter 1c is a converter that converts a speed deviation signal into an adjustment valve opening degree, and outputs an adjustment valve opening signal proportional to the speed deviation signal. Since the control valve opening signal outputted from the converter 1c is an electric signal, it is converted into a hydraulic signal by the electro-hydraulic converter 3, and is transmitted to the control valve 4, which adjusts the opening of the control valve 4 and sends it to the turbine 5. The amount of steam flowing in is controlled to control generator output or turbine speed.

When increasing the output of the generator 6, the speed of the turbine 5 connected to the power system 8 is determined by the frequency of the power system 8 and is constant, so if the speed load setter 1a is increased, the speed of the turbine 5 connected to the power system 8 is determined by the frequency of the power system 8, The speed deviation signal which is the output of 1b is increased, and the control valve opening signal of the converter IC is increased, and the opening of the control valve 4 is increased via the electro-hydraulic converter 3.
The amount of steam flowing into the turbine 5 is increased, the output torque of the turbine 5 is increased, and the generator 6 converts the steam into electricity to increase the generator output. That is, the output control of the generator 6 is performed by the speed load setting device 1a.
This can be done by increasing or decreasing.

On the other hand, the function of speed control by the speed governor 1 of the turbine electro-hydraulic control device when the frequency of the power system 8 fluctuates will be described below.

When the frequency of the power grid 8 increases, the frequency of the generator 6 connected to the power grid 8, that is, the speed of the turbine 5 increases. In the turbine electro-hydraulic control device, a speed increase of the turbine 5 is detected by the speed detector 2,
Since the speed deviation from the speed load setter 1a is determined by the adder 1b, as the speed of the turbine increases, the speed deviation signal which is the output of the adder 1b decreases, and the adjustment valve opening which is the output of the converter 1c decreases. The signal decreases, the opening degree of the control valve 4 decreases, the amount of steam flowing into the turbine 5 is decreased, the output of the turbine 5 decreases, and the frequency of the power system 8 is restored. As described above, when the opening degree of the regulating valve 4 changes due to frequency fluctuations in the power system 8, the output of the generator 6 fluctuates based on the load setting value set by the speed load setting device 1a.

FIG. 4 is a diagram showing the movement of the regulator valve 4 due to fluctuations in the frequency of the power system 8, that is, the speed of the turbine 5.
If the frequency increase rate is high, this indicates that there is a possibility that the regulator valve 4 may be throttled down to an opening degree that maintains the no-load rated speed in order to restore the frequency of the power system 8.

(Problem to be solved by the invention) The initial load of a generator immediately after being connected to the power system is generally several percent of the rated output, but during such low-load operation, the frequency of the power system suddenly increases. When the speed of the turbine increases by 1, the turbine electro-hydraulic control device outputs a control valve closing command to suppress the increase in turbine rotation. If the regulator valve is controlled in the closing direction during low-load operation, there is a possibility that the opening degree of the regulator valve will be closed below the no-load specified value, and there is a risk that the generator will motor.

The present invention detects that the generator is connected to the power grid,
After the generator is connected to the power grid, a lower limit is given to the regulator valve opening signal to maintain the no-load rated speed, with an opening of 10 α or more, to prevent the regulator valve from throttling due to an increase in the frequency of the power grid. It is an object of the present invention to provide a turbine electro-hydraulic control device that does not generate rings.

[Structure of the invention]

(Means for solving problems) FIG. 1 is an overall block diagram relating to the present invention.

In order to achieve the purpose of the above equation, in contrast to the prior art shown in FIG. A lower limit limiter 10 that prevents the limit from being narrowed down to below α, and a relay 11 that detects that the generator 6 is connected to the power system 8, and a switch 9 that sends an adjustment valve opening signal to the lower limit limiter 10 side. configured.

(Function) When the generator 6 is connected to the power system 8, that is, when the generator breaker 7 is open, it is connected to the converter 1c in the speed governor 1. The speed of the turbine 5 is adjusted to the speed setting value set by the speed load setting device 1a.
The speed deviation between the speed setting value of the turbine 8 and the speed of the turbine 8 detected by the speed detector 2 is obtained by the adder 1b, and converted into a control valve opening signal by the converter 1c.
The opening degree of the control valve 4 is adjusted through the control valve 4. The opening degree of the regulating valve 4 at this time is below the opening degree that maintains the no-load rated speed. When the generator 6 is connected to the power system 8, that is, when the generator breaker 7 is closed, the switch 9 is connected to the lower limit limiter 10 side. Immediately after the generator 6 is connected to the power system 8, the setting value of the speed load setting device 1a is the initial load (
The speed setting value corresponds to a few percent of the rated output). That is, the speed deviation signal that is the output of the adder 1b outputs a speed deviation corresponding to the initial load set by the speed load setting device 1a. The converter 1c converts the speed deviation signal corresponding to the initial load, which is the output of the adder 1b, into a control valve opening degree corresponding to the initial load, and outputs it to the lower limit limiter 10. The lower limit value of the lower limit limiter 10 is the opening degree + α that maintains the no-load rated speed.
Since the adjustment valve opening signal corresponding to the initial load from the conversion 1c is transmitted to the electro-hydraulic converter 3 without being lower limit limited by the lower limit limiter 10,
This is converted into a hydraulic signal, and the regulating valve 4 is opened by an opening corresponding to the initial load.

(Example) When the frequency of the power system 8 suddenly increases while the regulating valve 4 is opened to the opening degree corresponding to the initial load, as in the case of a double series, the speed of the turbine 5 increases by 1. The speed of the turbine 5 detected by the speed detector 2 increases, the speed deviation signal which is the output of the adder 1b decreases, and the control valve opening signal output of the converter 1c changes from the opening corresponding to the initial load to the closing direction. closed to
Lower limit limiter 1 maintains no-load rated speed even if the opening is below
Since the setting of 0 is the opening 10 α that maintains the no-load rated speed, the output of the lower limiter 10 is the opening degree + α that maintains the no-load rated speed, so the adjustment valve 4 is not closed below an opening of 10 α to maintain the no-load rated speed, so no motoring occurs.

Figure 2 shows that even if the regulator valve 4 throttles down to restore the frequency of the large power system 8 where the frequency of the power system 8 has suddenly increased, it will not be throttled down below the opening degree that maintains the no-load rated speed. ing.

〔Effect of the invention〕

According to the present invention, after the generator is connected to the electric power system, the opening degree of the adjusting valve is not limited to less than the opening degree of the adjusting valve set in the lower limit limiter, so the opening degree of the adjusting valve is not limited to the opening degree of the adjusting valve due to an increase in the frequency of the electric power system. Motoring of the generator can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an overall block diagram of the device according to the present invention, Fig. 2 is a characteristic diagram showing the movement of the control valve when the frequency of the power system increases when a lower limit limiter is provided according to the present invention, and Fig. 3 4 is an overall block diagram of the conventional device, and FIG. 4 is a characteristic diagram showing the movement of the control valve when the frequency of the power system increases in the conventional device. 1...Speed governor 1a...Speed load setter 1b...Adder IC/converter 2...Speed detector 3...Electro-hydraulic converter 4...Adjustment valve
5... Turbine 6... Generator 7
... Breaker 8 ... Power system 9 ... Switching device 10 ... Lower limit limiter 11 ... Relay agent
Patent Attorney Noriyuki Chika Yudo Ken Daishimaru

Claims (1)

[Claims] It has a speed governor that uses a converter to determine the degree of opening of the control valve based on the speed deviation between the speed setting value set by the speed load setting device and the turbine speed, and an electric signal from the speed governor is sent to an electro-hydraulic converter. In a turbine electro-hydraulic control device that converts the signal into a hydraulic signal and adjusts the opening degree of the adjusting valve to control the speed of the turbine or the output of the generator, the generator includes a switching means that is switched by opening and closing a generator or disconnector, and a generator. 1. A turbine electro-hydraulic control device comprising: a lower limit limiter that applies a lower limit to a control valve opening signal when a breaker is closed.