JPS6322132B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an initial load operation method for a power plant in a no-load state, and particularly to a system configured to transmit all of the power generated by the power plant to loads on the grid side only through the DC transmission system. The present invention relates to an initial load operation method for a power plant that starts up a DC transmission system and causes the power plant to take the initial load on the system.

FIG. 1 shows an example of the configuration of an AC/DC interconnection system. In Figure 1, PS is the power plant, T is the turbine, G is the turbine generator, Tr is the step-up transformer,
CB, CB _L1 and CB _L2 are AC line breakers, A and B are interconnected AC systems, ACLine 1 and ACLine 2 are interconnected AC transmission lines, and Bus 1 to Bus 3 are AC buses. Also,
On the DC transmission system side, C/Tr is a converter transformer, V is an AC/DC converter, DCL is a DC reactor,
DCLine indicates the DC transmission line, P _G indicates the turbine generator output, and Pd indicates the DC transmission system operating power.

Conventionally, even in systems where power plant output is transmitted through a DC transmission system, as shown in Figure 1, the AC bus of the power plant PS or the AC side bus Bus 1 of the converter of the DC transmission system is connected to the interconnected AC transmission line. ACLine 1 is connected and the system is configured so that power generated by the power plant can be transmitted even on an AC system. Then, the turbine generator G of the power station PS is first synchronously connected to the AC system and applies an initial load on the system side, then starts the load, starts the DC transmission system, and then loads the AC system. A method is being taken to gradually transfer power to the DC transmission system, and the power plant's turbine T
The initial load operation of the turbine generator G is not particularly different from that of a conventional AC grid-connected power plant.

However, in the system shown in Figure 1,
In a state where the edge disconnector, CB _L1 , or edge disconnector CB _L2 of the AC transmission line ACLine1 connected to the AC bus bus Bus1 on the transmission end side of the DC transmission system is OFF, or when the AC transmission line ACLine1 In a system configuration in which no In order to make the turbine T and turbine generator G of the power station PS, which are in load operation, take the initial load on the system, start the DC transmission system and operate the turbine T and turbine generator G at a load equivalent to the initial system load. There must be.

By the way, in general, the AC/DC converter V of the DC transmission system
It is possible to perform operation in which a DC current of a predetermined value or more is passed and the DC voltage is almost zero, that is, zero power factor operation that does not consume active power. (hereinafter referred to as "transducers") are expensive. Furthermore, when using a converter that does not have the ability to operate at zero power factor for long periods of time, it is necessary to flow a DC current of a predetermined value or more immediately after startup, and to raise the DC voltage within a short period of time. The load corresponding to the rise of the DC voltage will be taken from the AC system that serves as the power source.

On the other hand, even when the initial load is applied to turbines and turbine generators in power plants, there is a time delay of several seconds or more due to delays in the operation of steam flow control valves and the characteristics of the turbine and turbine generator. Output with . Therefore, when performing initial load operations on the turbines and turbine generators after the power plant turbines and turbine generators have reached their rated speed after startup, appropriate timing and load start-up must be taken into account when adjusting the DC transmission system. It is requested to start.

FIG. 2 shows a time chart when the DC transmission system load Pdc is started by starting the DC transmission system at the same time as the initial load operation. In the figure, the DC transmission system load Pdc is the turbine generator output
Because it starts up before P _G , the output of the turbine and turbine generator cannot catch up, and the frequency at which the rotational energy does not exceed the deficit ΔE _TG decreases.
This shows that the frequency deviation ΔF with respect to the rated frequency fluctuates greatly when ΔF<0, and it is possible that the turbine generator may drip in some cases.

The present invention was made in view of the above-mentioned demands, and its purpose is to start up a DC power transmission system to which an AC/DC converter for DC power transmission, which does not have long-term zero power factor operation capability, can be used to power a power plant. An object of the present invention is to provide an initial load operation method for a power plant that can safely and stably apply an initial load to a grid turbine generator.

First, the concept of the present invention will be described. FIG. 3 is a block diagram showing the concept of a turbine and a turbine generator system mainly consisting of a steam system in a thermal power plant or a nuclear power plant. In Figure 3, B is the boiler or reactor steam generation section, C is the condenser, T is the turbine, G is the turbine generator, V _S is the main steam stop valve, V _SP is the main steam isolation valve, and V _C is the Steam control valve, V _B
indicate steam bypass valves, respectively. In the figure, the turbine T is accelerated to the rated speed by opening the main steam stop valve V _S , the main steam isolation valve V _SP , and the steam bypass valve V _B , and adjusting the steam control valve V _C. If the power plant is connected to an AC system that serves as a load, the turbine generator G, which has reached its rated speed, joins the AC system synchronously, and then the steam control valve V _C and the steam bypass valve
The initial load will be taken by adjusting the opening of _VB .
However, this initial load operation depends on the operation and operation delay time of the steam control valve V _C and steam bypass valve V _B , the input/output response characteristics of the turbine T and the turbine generator G, etc. There is a time delay on the order of several seconds before the initial load is applied as an output. Because of this delay time, if the system configuration is such that the power plant takes on the load only via the DC transmission system, it is necessary to ensure an appropriate start-up timing of the DC transmission system.
In addition, when a converter in a DC power transmission system is started, it immediately sets the DC current to a predetermined value, and if it does not have the ability to operate at zero power factor for a long time, it is necessary to ramp up the DC voltage within a short period of time. will be taken.
Therefore, it is necessary to properly start up the DC voltage.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram showing a circuit configuration for starting the DC power transmission system according to the present invention and applying an initial load to the turbine generator of the power plant. In Fig. 4, T is a turbine, G is a turbine generator, Tr is a step-up transformer,
C.Tr indicates a converter transformer, V indicates a converter, DCL indicates a DC reactor, and PD indicates a voltage transformer. Also,
1 is an operation control device for steam control valves of turbine T;
2 is a frequency detection device, 3 is an AND gate circuit, 4
1 and 2 show control devices for the DC power transmission system, respectively. Here, the frequency detection device 2 is configured as follows. The voltage signal from the grid is converted to a frequency −
It is input to the voltage converter FVC and converted to a DC voltage proportional to the frequency, and the reference frequency signal F・R (however,
(DC voltage signal) and inputs it to comparator C. This comparator C operates when an input equal to or greater than the value Δs set by the setter LS is received, and is configured to operate when the frequency deviation ΔF input exceeds the set value Δs. Further, the control device 4 for the DC power transmission system includes a starting control circuit 41, a limiter circuit 42, and an operation control circuit 43.

Next, a method for operating the initial load on a power plant system according to the present invention will be described. In FIG. 4, the generator turbine G is started up as described in FIG. 3 and reaches its rated speed. Thereafter, a command is given to the steam control valve operation control device 1 to adjust the openings of the steam control valve V _C and the steam bypass valve V _B shown in FIG. 3, and to issue an operation signal for applying an initial load. A command signal or operation signal for the initial load operation is obtained from the operation control device 1. On the other hand, when the steam control valve V _C and the steam bypass valve V _B are controlled by the initial load operation signal and the steam flow rate to the turbine T increases,
Turbine T and turbine generator G in no-load state
is accelerated, and the output frequency of the turbine generator G increases. For this reason, the primary side voltage of the converter transformer C/Tr (AC bus voltage may be used) is transferred to the voltage transformer.
The PD detects the output voltage, inputs the output voltage to the frequency detection device 2, determines that the frequency has increased by more than a predetermined value, outputs it, and adds it to the AND gate circuit 3 as one input. Further, as the other input of the AND gate circuit 3, an initial load command signal or an operation signal from the operation control device 1 is applied. Then, on the condition that the AND condition of the AND gate circuit 3 is satisfied, the output is transmitted to the startup control circuit 41 in the control device 4 of the DC power transmission system.
is given as a startup command to start up the DC transmission system, and the limiter circuit 42 controls the DC voltage of the DC transmission system at an appropriate rate of change to maintain the load at a predetermined value (the allowable initial load level of the turbine generator G). ). Therefore, after the initial load operation of the turbine T, it is detected that the output frequency of the turbine generator G begins to increase, that is, this appears as a change in the output of the turbine T and the turbine generator G, and the DC transmission system , so there is no need to worry about the timing of starting the DC transmission system. In addition, the load change of the DC transmission system, which is brought up to a predetermined value at the time of startup, is controlled by the operation control circuit 43 in consideration of the initial load permissible level and response characteristics of the turbine T and turbine generator G. By setting the DC current level and setting the DC voltage to rise at an appropriate rate of change in the limiter circuit 42, coordination between the turbine generator output rise and the start-up load of the DC transmission system can be achieved. Therefore, frequency fluctuations at the time of initial load can be suppressed.

FIG. 5 shows the above explanation in the form of a time chart. In the figure, Pdc is the transmitted power of the DC transmission system, P _G is the turbine generator output power,
ΔF indicates the frequency deviation from the rated frequency,
Δs means the set level of the frequency detection device 2 in FIG. In other words, this figure shows that after the initial load operation, the turbine generator output frequency is Δs from the rated value.
When the frequency increases, the frequency detection device 2 operates to output an output, and the DC power transmission system is activated, indicating that the change in the turbine generator output frequency is suppressed.

In this way, in a system in which the power generated by a power station PS equipped with a turbine T and a turbine generator G is transmitted only through the DC transmission system, a power station PS that is in a no-load operating state or an operating state close to it is
In the case where the turbine generator G of
Equipped with a frequency detection device 2 that detects the frequency of the AC bus of the PS or the AC bus of the power transmission end converter station of the DC transmission system, determines that the frequency has increased by a predetermined value or more, and outputs the output, and steam control for initial load operation. The valve operation control device 1 is commanded to operate the steam control valve V _S and the steam bypass valve V _B of the generator turbine T, and the command signal or operation signal is obtained so that the generator turbine T receives the initial load. On the condition that the turbine generator output frequency has increased by a predetermined value or more, the controller 4 of the DC power transmission system is commanded to start the DC power transmission system, and the permissible initial load level of the turbine generator G is set. By controlling the rise of the DC voltage, the load on the DC power transmission system is increased at an appropriate rate of change, and the initial load operation of the turbine generator G of the power plant is performed.

FIG. 6 shows the structure of another embodiment of the present invention. In the figure, 41' is a starting control circuit;
2' is a start limiter control circuit in the control device 4 of the DC power transmission system, etc., which controls the rise of the DC voltage at startup, 43' is the operation control circuit of the DC power transmission system, and other elements are as follows. It is similar to FIG.

That is, in this method, in FIG. 6, an initial load operation command signal or operation signal is obtained from the operation control device 1 for the steam control valves of the turbine, and is applied to the startup control circuit 41 to bring the DC power transmission system into a zero power factor operating state. In other words, it is started with a predetermined DC current flowing and the DC voltage being zero. In such a situation, turbine generator G does not need to supply active power. Thereafter, the turbine generator output frequency begins to increase, which is detected by the frequency detection device 2 which receives the grid voltage signal as input, and a command is sent to the limiter circuit 42 via the AND gate 3 to set the DC voltage to the preset value. The DC voltage is increased at an appropriate rate of change, that is, in coordination with the output power rise characteristics of the turbine generator G, the DC power transmission system is increased, and the initial load (active power load) is applied to the turbine generator G.
This is a method similar to applying .

Such a turbine T and a turbine generator G
In a system in which the generated power of a power plant PS equipped with When the initial load is taken on the system, the above power station PS
A frequency detection device 2 that detects the frequency of an AC bus or an AC bus at a power transmission end conversion station of a DC transmission system, determines that the frequency has increased by a predetermined value, and outputs the result.
and commands the steam control valve operation control device 1 to operate the steam control valve V _S and steam bypass valve V _B of the generator turbine T for initial load operation, and obtains the command signal or operation signal. , adds an operation to apply an initial load to the generator turbine T, and also instructs the control device 4 of the DC transmission system to start the DC transmission system in a zero power factor operating state, so that the output frequency of the turbine generator is set to a predetermined value. On the condition that the voltage has increased by more than the specified value, the controller 4 is commanded to control the DC transmission voltage of the DC transmission system in coordination with the rise characteristic of the turbine generator output power, thereby starting up the load at an appropriate rate of change. In this way, the initial load operation of the power plant is performed.

Although the frequency detection device 2 in FIGS. 4 and 6 above uses a frequency deviation level detection method, it is not limited to this, and may also use a frequency absolute value detection method or a frequency change rate detection method. Of course, it is possible. In addition, in FIG. 6 above, the initial load operation command signal or operation signal is given to the startup control circuit 41 as the startup command, but as this startup command, a manual operation command or an appropriate operation command is given to the initial load of the power plant. It may be applied to the startup control circuit 41 before operation to start the DC power transmission system in a zero power factor operating state.

In addition, the present invention can be implemented with various modifications without changing the gist thereof.

As explained above, according to the present invention, it is possible to suppress frequency fluctuations of a turbine generator in a power plant by starting a DC power transmission system to which an AC/DC converter for DC power transmission, which does not have long-term zero power factor operation capability, is applied. It is possible to provide a highly reliable initial load operation method for a power plant that can safely and stably apply an initial load to the system.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing a general AC/DC interconnection system.
Fig. 2 is a time chart for explaining the drawbacks of the prior art, Fig. 3 is a conceptual diagram showing the concept of the present invention, Fig. 4 is a block diagram showing an embodiment of the present invention, and Fig. 5 is a diagram of the present invention. FIG. 6 is a time chart diagram for explaining the operation of the invention, and FIG. 6 is a block diagram showing another embodiment of the invention. 1... Operation control device, 2... Frequency detection device,
3...AND gate circuit, 4...DC transmission system control device, 41, 41'...Start control circuit, 42,
42'... Limiter circuit, 43, 43'... Operation control circuit.

Claims (1)

[Claims] 1. A turbine generator of a power plant that is in a no-load operating state or an operating state close to it in a system in which the generated power of a power plant equipped with a turbine generator is transmitted only through a DC transmission system. When starting up the DC transmission system to take the initial load on the system, detect the frequency or frequency deviation of the AC bus of the power plant or the AC bus of the transmission end converter station of the DC transmission system, and the frequency increases by a predetermined value or more. Equipped with a frequency detection device that determines whether the change has occurred or is changing in an increasing direction and outputs an output, which instructs the steam control valve operation control device for initial load operation to control the steam control valve and steam bypass of the generator turbine. When the valve is operated and the command signal or operation signal is obtained, the generator turbine enters an operation to apply an initial load, and the turbine generator output frequency increases by more than a predetermined value or changes in an increasing direction. Start the DC transmission system by instructing the control device of the DC transmission system under the condition that An initial load operation method for a power plant characterized by starting up at a certain rate. 2 In a system in which the power generated by a power plant equipped with a turbine generator is transmitted only through the DC transmission system, the DC transmission system is activated to the turbine generator of the power plant that is in a no-load operation state or a similar operating state. When the initial load is taken on the system, the frequency or frequency deviation of the AC bus of the power plant or the AC bus of the transmission end side converter of the DC transmission system is detected, and the frequency is determined to be higher than a predetermined value or in an increasing direction. It is equipped with a frequency detection device that determines and outputs a frequency change, and for initial load operation, it commands the operation control device of the steam control valves to operate the steam control valve and steam bypass valve of the generator turbine. Obtaining a command signal or an operation signal, performs an operation to apply an initial load to the generator turbine, and also instructs the control device of the DC transmission system to start the DC transmission system in a zero power factor operating state, and Under the condition that the generator output frequency has increased by more than a predetermined value or is changing in an increasing direction, the control device is commanded to coordinate the DC power transmission voltage of the DC power transmission system with the rise characteristics of the turbine generator output power. An initial load operation method for a power plant, characterized in that the load is started up at an appropriate rate of change by controlling the load. 3. The power plant according to claim 2, wherein a manual operation command or an appropriate operation command is given before the initial load operation of the power plant to start the DC transmission system in a zero power factor operating state. Initial load operation method.