JPS6322133B2 - - 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 for a system configured to transmit all of the power generated by the power plant to the load on the grid side only through a DC transmission system. , 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 a DC transmission line, P _G indicates the turbine generator output, and P _d 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 station PS or the AC side bus of the converter of the DC transmission system is
Bus1 is connected to interconnection AC power transmission line ACLine1, and is configured to be able to transmit power generated by the power plant even in 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 has been adopted in which the power plant is gradually transferred to a DC power transmission system, and the initial load operation of the turbine T and turbine generator G of the power plant is not particularly different from that of a conventional AC interconnected system 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 plant PS, which are in load operation, take on the initial system load, the DC transmission system must be started and operated at a load equivalent to the system initial load of the turbine T and turbine generator G. 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 draw any active power. (hereinafter referred to as "transducers") are expensive. In addition, when using a converter that does not have the ability to operate at zero rate for a long period 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 AC system that serves as the power source will take a load corresponding to the rise of the DC voltage.

On the other hand, even if the initial load is applied to turbines, turbine generators, etc. of power plants, it may take 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 a delay. Therefore, when performing initial load operation on the turbines and turbine generators after the power plant turbines and turbine generators have reached their rated speed after startup, DC power transmission should be carried out with appropriate timing and load start-up in mind. It is desired to activate the system.

FIG. 2 shows a time chart when the DC power transmission system is started at the same time as the initial load operation to start up both the DC currents I _dc and E _dc to start up the DC power transmission system load P _dc . In the figure, the DC transmission system load P _dc rises before the turbine output P _T , so the turbine output cannot catch up and the rotational energy does not cover the deficit ΔE _TG , so the frequency of the turbine generator decreases. This indicates that the frequency deviation ΔF 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 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 double water tank, 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 main steam isolation valve. 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 that has reached its rated speed will synchronously join the AC system, 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 must immediately set the DC current to a predetermined value, and if it does not have long-term zero power factor operation capability, it must raise the DC voltage within a short time. It will take a load. Therefore, it is necessary to properly start up the DC voltage.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing a circuit configuration according to the present invention for starting a DC power transmission system and causing a turbine generator in a power plant to take the initial load on the system. In the figure, 1 is the generator turbine steam control valve V _C , which is commanded for initial load operation.
An operation control device that generates operation signals to operate and control various steam control valves such as steam bypass valve _VB ,
A signal indicating that the operation signal has been issued is sent out via the signal transmission means 2. 3 is this signal transmission means 2
This is a delay circuit which inputs the (operation) signal transmitted through the )
control device 5, and the AC/DC converter V is controlled by the control output thereof. Here, the delay circuit 3 is a circuit that sets the delay time td from the initial load operation of the turbine until it can be extracted as the turbine generator output, and the delay circuit ₃ is a circuit that sets the delay time _td from the initial load operation of the turbine to the time when it can be extracted as the turbine generator output. This time is set in consideration of the output delay time determined from the input/output response characteristics of the turbine and turbine generator. The control device 5 also includes a startup control circuit 51, a limiter control circuit 52 that controls the DC voltage (of the DC transmission system) during startup and shutdown, and an operation control circuit 53 that includes basic control and phase control. be.

Next, a method for operating a system initial load in a power plant according to the present invention will be described. In Fig. 4, in order to apply an initial load to the turbine T and the turbine generator G, which have been started and reached the rated speed without load as explained in Fig. 3, the steam control valve V _C is opened to a predetermined value. At the same time, it commands the operation control device 1 to close the steam bypass valve _VB and issues an operation signal, and also sends a signal indicating that the operation signal has been issued to the delay circuit 3 via the signal transmission means 2. Give it and make it work. The output of this delay circuit 3 is sent out and given to an AND circuit 4 after a set time td has elapsed. Furthermore, since the input side signal of the delay circuit 3 is also input to this AND gate circuit 4,
Provided that the delay circuit 3 sends out an output and the command is reliably output, sends out the output and sends a command to the startup control circuit 51 of the DC power transmission system control device 5 to start up the DC power transmission system. give.

FIG. 5 shows the above explanation in the form of a time chart. In the figure, at t=to, the initial load operation is started by a signal from the operation control device 1 in Figure 4, but the turbine generator output is
Due to the operation delay of V _C , the steam bypass valve V _B , and the input/output response characteristics of the turbine/turbine generator, the turbine generator output is delayed by a time t _G. If the settling time limit td of the delay circuit 3 is td = t _G , the DC transmission system will also be activated when the turbine generator output power can be taken out, so the rate of increase in the turbine output and the rate of increase in output power at the time of starting the DC transmission system will be The difference becomes the disturbance energy ΔE _TG of the turbine generator and changes the rotation speed, that is, the frequency, resulting in a frequency deviation ΔF. Therefore, delay circuit 3
By setting the settling time td and the rate of change of power at startup of the DC transmission system to appropriate values, the turbine generator output frequency deviation ΔF, that is, the frequency disturbance, can be made extremely small, resulting in a stable turbine generator. An initial load operation is performed.

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
When the turbine generator G starts the DC transmission system and takes the initial load of the system, the steam control valve operating device 1 is commanded to operate the steam control valves V _S and of the generator turbine T for the initial load operation. In addition to operating the steam bypass valve V _B , the command signal or operation signal is output to an output determined from the operation delay time characteristics of the steam control valve V _S and the steam bypass valve V _B , and the input/output response characteristics of the turbine T and turbine generator G. A delay time td (=t _G ) determined from the delay time is applied to the control device 5 of the DC transmission system through the set delay circuit 3 to start the DC transmission system, and the turbine generator G is controlled to reach the permissible initial load level. The load on the DC power transmission system is increased at an appropriate rate of change by controlling the rise of the DC voltage.

FIG. 6 shows a configuration of another embodiment according to the present invention, and the same parts as in FIG. 4 are denoted by the same reference numerals. In FIG. 6, a command signal or operation signal for the initial load operation is obtained from the steam valve operation control device 1, and is sent to the startup control circuit 51 in the control device 5 of the DC power transmission system through the signal transmission means 2. Then, the DC power transmission system is started in a zero power factor operation state at the DC current level determined by the operation control circuit 53, and an appropriate delay time td is set after the turbine initial load operation until it can be taken out as the turbine generator output. The delay circuit 3 is driven. and a given time
After td has elapsed, the output of the delay circuit 3 is given to the limiter control circuit 52 of the control device 5 of the DC transmission system,
By raising the DC system voltage at an appropriate rate of change, the AC/DC converter V is controlled so that the DC transmission system load matches the initial load output characteristics of the turbine generator.

The load conditions of the generator and the DC power transmission system due to the above operation are shown in the time chart of FIG. 7. In Figure 7, P _dc is the load of the DC transmission system, I _dc is the DC current, E _dc is the DC voltage, and P _T
is the turbine output, ΔF is the deviation of the actual frequency from the rated frequency of the turbine generator,
ΔE _TG indicates the deviation between the DC transmission system load and the turbine output, that is, the load that can be output from the generator, and the larger this value, the greater the frequency disturbance.

In Fig. 7, at time t = to, the initial load operation is performed on the turbine generator, and the DC voltage E _dc 0 and DC current I _dc = I _dnio are applied to the DC transmission system.
In other words, zero power factor operation is started, and delay circuit 3 is activated.
This shows that by raising the DC voltage after the settling time td has elapsed, the load can be raised at an appropriate rate of change.

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
When the turbine generator G starts the DC transmission system and takes the initial load of the system, the steam control valve operating device 1 is commanded to operate the steam control valves V _S and of the generator turbine T for the initial load operation. In addition to operating the steam bypass valve V _B , the command signal or operation signal is output to an output determined from the operation delay time characteristics of the steam control valve V _S and the steam bypass valve V _B , and the input/output response characteristics of the turbine T and turbine generator G. The delay time td (=t _G ) determined from the delay time is given to the set delay circuit 3 to drive it, and the DC power transmission system is started to flow a predetermined DC current in a zero power factor operation state, and the DC power transmission system control device 5
By controlling the DC voltage of the DC transmission system to rise to the rated value, the load is started at an appropriate rate of change up to the permissible initial load level of the turbine generator G. .

In the above, the function of the delay circuit 3 is not limited to the control device 5 of the DC power transmission system even if it is provided on the operation control device 1 side.
Of course, the same effect can be obtained even if it is provided on the side.

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

As explained above, according to the present invention, 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 is activated, thereby suppressing frequency fluctuations of a turbine generator in a power plant. It is possible to provide an extremely 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 block diagram showing another embodiment of the present invention, and FIG. 7 is a time chart explaining the action in FIG. 6. 1... Operation control device, 2... Signal transmission means, 3
...Delay circuit, 4...AND gate circuit, 5...
DC power transmission system control device, 51...start control circuit, 52...limiter control circuit, 53...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 an initial load on the system, the system instructs the steam control valve operating device to operate the steam control valve and steam bypass valve of the generator turbine for the initial load operation, and also operates the steam control valve and steam bypass valve of the generator turbine. A command signal or an operation signal is transmitted through the DC power transmission through the delay circuit in which the delay time determined from the output delay time determined from the operation delay time characteristics of the steam control valve and the steam bypass valve and the input/output response characteristics of the turbine and turbine generator is set. The DC power transmission system is supplied to a control device of the system to start the DC transmission system, and the load on the DC transmission system is increased to the permissible initial load level of the turbine generator at an appropriate rate of change by controlling the rise of the DC voltage. An initial load operation method for a power plant, which is characterized by: 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 applied to the system, the system instructs the operating device of the steam control valves to operate the steam control valve and steam bypass valve of the generator turbine for the initial load operation, and also transmits the command signal or operation signal. A delay time determined from an output delay time determined from the operation delay time characteristics of the steam control valve and the steam bypass valve and the input/output response characteristics of the turbine and turbine generator is applied to the set delay circuit to drive it, and the DC power transmission is performed. The system is started to flow a predetermined DC current in a zero power factor operating state, and the load is controlled to an appropriate level by instructing the control device of the DC transmission system to raise the DC voltage of the DC transmission system to the rated value. An initial load operation method for a power plant, characterized in that the initial load operation method for a power plant is performed by ramping up the turbine generator to an allowable initial load level at a rate of change.