JPS60249900A - Output control system of atomic power generator connected with dc system - Google Patents

Abstract

PURPOSE:To prevent an atomic reactor from stopping due to overspeed of a turbine by rapidly throttling a control valve to reduce the input of the turbine when a DC system is stopped and rapidly opening the valve when the DC system is restarted. CONSTITUTION:The output command value of a generator from a central power supply station is compared with the sum of transmission enabling power of transmission lines, and smaller value is applied as a load set value of the generator to an automatic load regulator 101. On the other hand, the output of a time delay circuit 11 which inputs a load set value is compared with the load set value, and a bias signal in response to the difference is applied to a control valve control signal if the difference is the prescribed value or higher. Thus, it can prevent an atomic reactor from stopping due to the overspeed of the turbine.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a system for transmitting DC power from a nuclear power generator, in which the DC system is temporarily stopped, the turbine control valve of the nuclear power generator is closed, and the The present invention relates to a method for suppressing speed increase by rapidly closing a turbine control valve when a bypass valve is opened, and a method for quickly restoring transmitted power by restarting a DC system.

[Background of the invention]

Due to locational issues, large-capacity power sources for power systems are installed in remote locations, and there is a tendency to use economically advantageous nuclear power generators as generators. As a power transmission method, DC power transmission is planned, which is advantageous for large-capacity power transmission from remote areas.

Figure 1 shows this DC transmission system. 11Fi nuclear power generator, 12~14Fi power receiving side generator, 21~28
31.32 is a forward converter for AC/DC conversion; 41. is a transformer; 31.32 is a forward converter for AC/DC conversion;
42 is an inverse converter for AC/DC conversion, 51 to 53 are loads, 61
indicates the failure point of the DC transmission line.

Although a system that transmits the output of a nuclear power generator as DC power as shown in Figure 1 has not yet been realized, if a failure 61 occurs, the forward and reverse converters 32 and 42 are activated in the same way as in the control of a general DC system. It is believed that it is necessary to temporarily stop the generator, restart it at high speed after the fault disappears, and suppress the increase in generator speed due to a decrease in the generator load. The problem on the nuclear power generator side in this case is discussed in the second section.
This will be explained with reference to FIG. In Fig. 2, 11 to 32 are the same as in Fig. 1, 71 is a nuclear reactor, 72 is a turbine, 73 is a condenser,
81 is a control valve, 82 is a bypass valve, 91 is a low value gate,
101 indicates an ALR (automatic load adjustment device). The output of the reactor is output according to the output setting value of the generator, and the regulating valve is controlled so that the pressure caused by this output is constant. The signal from the speed deviation side of the generator has a bias of about 10% to the load set value, and the upper pressure set value is normally applied to the low value gate 91 to control the control valve. The signal from the speed deviation side is selected when the speed becomes higher than the rated value by about 0.5% or more.

When connected to a normal AC system, the speed of a nuclear power generator is kept constant by controlling the speeds of other generators. If the nuclear power plant is connected to the power grid only through the DC system, add the signal from the generator speed deviation to the DC system forward converter output setting value to adjust the generator speed to the rated value, as shown in Figure 3. The output of the DC system, that is, the output of the generator, is controlled so that the

If a failure occurs at 61 in FIG. 1, the forward and inverse converters 32 and 42 are temporarily stopped as described above, and restarted quickly after the failure disappears. In this case, the failure usually disappears in less than one second, and it is thought that it takes about one second from the occurrence of the failure to the completion of restart. When the converter is stopped, the generator load decreases, the speed increases, the control of the control valve 81 in FIG. 2 changes from a pressure-based loop to a speed-based loop, and the control valve 81 is closed.

However, the period during which the generator load is reduced due to a failure is short, and once the restart is complete, the regulating valve returns to pressure control and hardly operates.

However, if the proportion of faulty systems is large and the speed increases rapidly, failure recovery is delayed, or high-speed restart fails for some reason and the change in the control signal of the regulator valve 81 is large due to the generator speed increase, the regulator valve 81 control signal changes greatly. It is rapidly throttled and the bypass valve 82 of FIG. 2 opens.

A reactor with a full-capacity bypass valve with a large bypass valve capacity can continue to operate even if the regulator valve is rapidly throttled, but a reactor with a partial-capacity bypass valve with a small bypass valve capacity can continue operating even if the regulator valve is rapidly throttled beyond the bypass valve capacity. If the flow rate of steam to the turbine is reduced by closing the reactor, the reactor pressure will increase, the neutron flux will increase, and the reactor will be scrammed (shut down), and it will take a long time to produce output again.

In addition, even for a reactor with a full capacity bypass valve, if the ratio of power transmission system outages is large, the speed will increase significantly, and if the speed increases by about 10% or more, the reactor will not have to be shut down. A method that further suppresses speed increases is desirable.

[Purpose of the invention]

The purpose of the present invention is to rapidly reduce the turbine input by the necessary amount when the output of a nuclear power plant decreases due to a shutdown of the DC system, to prevent the reactor from shutting down due to turbine overspeed, and to increase the speed by restarting the DC system. The goal is to restore transmitted power.

[Summary of the invention]

When all or part of the DC system is stopped and recovery from the failure is delayed, the present invention rapidly operates the regulating valve to reduce the turbine input by the difference between the power before the DC system stopped and the power that can be transmitted through a healthy line. When the failed DC system is restarted, the control valve is controlled to open rapidly by the corresponding increase in power transmission power.

In this case, the turbine input due to the sudden closing of the regulating valve may suppress the acceleration of the generator more quickly as the power transmission coefficient α is reduced due to the DC system failure. Also, priority is given to quick closing of the control valve of a turbine having a full capacity bypass valve over the control valve of a turbine having a partial bypass valve.

[Embodiments of the invention]

Embodiments of the present invention are shown in Figures 4 to 6. In Figure 4, the generator output command value from the intermediate supply and the sum of the transmittable power of each transmission line are compared, and the smaller value is selected. This is the generator load setting value. Each power transmission line is excluded from the sum of transmittable power while it is unable to transmit power due to a failure, and is added to the sum when restarted.

In FIG. 5, 91 to 101 are the same as in FIG. 2, and 111 represents a time delay circuit. If the load set value in FIG. 4 is simply changed to the load set value in FIG. 2, it will be difficult to change the set value actually applied to the generator due to ALRIOI. To avoid this, as shown in Figure 5, the difference between the negative set value and the value passed through the load set value time delay circuit 111 is taken, and when the load set value suddenly decreases, a command is temporarily sent to the speed signal side. and close the control valve at high speed. This signal over time.

The command value from the ALRIOI side changes from zero to zero. If the command temporarily given to the speed signal side is below a certain level, the input to the speed signal side will be cut off, and if this input is present, the bias of the load setting value, which is about 10%, will be temporarily changed. (for example, set the bias to zero). This causes rapid control of the control valve and suppresses the speed increase of the generator.

FIG. 6 is an embodiment of a control method when transmittable power decreases due to a DC system failure when there is a generator having a partial capacity bypass valve. In FIG. 2, FIG. 4, and FIG. 5, the generators are explained as one unit, but in reality, several generators are usually operated in parallel. If one of these generators has a partial capacity bypass valve, as shown in Figure 6, the load setting value of the entire generator group after a DC system failure is set to fully open the bypass valve of the generator with the partial capacity bypass valve. For combinations of generators that have as many partial capacity bypass valves as necessary, the output is smaller than the previous output, and if this condition continues for longer than time T, the control valve is fully closed and the generators are stopped, and the remaining generators are continue to operate.

Another example of a control method when there is a generator with a partial capacity bypass valve will be described. When there is a sudden decrease in the load setting value in Fig. 5, the time delay circuit 11 between the load setting value and the load setting value
When there is an output from the circuit that takes out the difference from the value passed through 1, the bias of the load setting value is changed. A difference is added to this bias value and the control valve is closed accordingly. For example, all generators with full capacity (Ibus valve) have a bias of 10 cm →
Generator A, which has a partial capacity bypass valve, remains unchanged at 10 cm, and generator B changes from 10% to 20%. As a result, when the load setting value suddenly decreases, the generator with a full capacity bypass valve and the generator A1 with a partial capacity bypass valve
Similarly, the control valves are closed in the order of B, and if all machines cannot continue operating, generators A and B are stopped in that order.

Furthermore, if the output of the reactor itself is reduced, even if the fault in the DC system is recovered, it will take a long time to increase the reactor's output again, and during that time the generator will not be able to output the necessary power.

In order to avoid this, there is a method in which the load setting value for the reactor is changed only when a failure continues for a set period of time.

Note that the above explanation has been given for the case of only a nuclear power generator, but even if a thermal power plant or a hydraulic power plant is included, this may be treated as a power generator whose output is preferentially reduced like a power generator having a full capacity bypass valve. Furthermore, even if the power transmission line has AC as well as DC in parallel, it can be treated in the same way by adding the power that can be transmitted in Figure 4 according to the limit of the power transmission capacity of the AC system.

〔Effect of the invention〕

As described above, according to the present invention, when transmitting nuclear power generator output by direct current, the possibility of nuclear reactor shutdown is reduced when all or part of the DC system fails and a rapid restart is not possible, and the nuclear power generator is This allows for more stable operation.

[Brief explanation of the drawing]

Figure 1 is an example of a system targeted by the present invention, Figure 2 is the configuration of a nuclear power generation device connected to a DC system, Figure 3 is an explanation of the method for setting the output of a forward converter, and Figures 4 and 6 are The figure is an explanation of a generator load setting method showing an embodiment of the present invention, and FIG. 5 is a control method of a turbine control valve showing an embodiment of the present invention. 11... Nuclear power generator, 12-14... Power receiving side generator, 21-28... Transformer, 31-32... Forward converter, 41-42... Inverse converter, 51- 53... Load, 61... Failure point, 71... Nuclear reactor, 72... Turbine, 73... Condenser, 81... Control valve, 82...
...Bypass valve, 71 diagram ￥3 diagram

Claims (1)

[Claims] 1. In a system that transmits all or part of the generated power from a power source including a nuclear power generator via a DC transmission line, when all or part of the DC system is stopped, the power before the DC system is stopped is When power cannot be transmitted over a healthy circuit, the nuclear power generator is designed to reduce turbine input by the difference between the power before the DC system is stopped and the power that can be transmitted through a healthy circuit, plus α (α is the margin for decelerating the accelerated generator). The DC system is characterized by rapidly throttling the regulator valve of the turbine, detecting when the failed DC system restarts, and controlling the regulator valve to rapidly increase the electric power commensurate with the increase in transmitted power. Output control method for connected nuclear power generators. 2. In claim 1, when suddenly closing the regulating valve, priority is given to the generator, and even if the regulating valve is drastically throttled, there is no risk of causing a reactor scram. Prioritize closure, and if the generator output range due to rapid throttling of the regulator valve is insufficient, the regulator valve is increased by more than the capacity of the bypass valve to achieve the minimum output combination that is larger than the required output range. An output control method for a nuclear power generator connected to a direct current system, characterized by completely closing a regulator valve of the generator, which has a partial capacity bypass valve that causes the reactor to scram when throttled. 3. In the nuclear power generator according to claim 1, when the control valve is suddenly closed, priority is given to the generator,
The priority is to quickly close the regulator valves of generators so that the reactor will not be scrammed even if the regulator valves are significantly throttled, and for generators with partial capacity bypass valves, priority is given to each generator, and all generators are closed at the same time. An output control method for a nuclear power generator connected to a direct current system, characterized in that a generator having a partial capacity bypass valve is controlled so as not to reach a scram condition. 4. When the regulator valve is suddenly closed in the nuclear power generator according to claim 1, when the load suddenly decreases for only a short period of time, such as when a faulty DC system successfully restarts at high speed, the output of the reactor does not change. An output control method for a nuclear power generator connected to a DC system, characterized by not giving a reduction command.