Power generation system

Abstract

To provide a power generation system capable of solving or improving a problem related to a start-up time of a generator.SOLUTION: A power generation system 1 includes a power generator 2, an automatic voltage adjuster 3, a voltage converter 4, a first breaker 51 for opening and closing a first current path L1 between the voltage converter 4 and a power system, and a second breaker 56 for opening and closing a second current path L2 between the power generator 2 and the voltage converter 4. The power generation system 1 is capable of selectively executing a first connection scheme in which the second breaker 56 is brought from an open state into a closed state after the first breaker 51 is brought into a closed state, and a second connection scheme in which the first breaker 51 is brought from an open state into a closed state after the second breaker 56 is brought into a closed state, and the automatic voltage regulator 3 sets a start-up time of the generator 2 when the first connection scheme is executed to be shorter than a start-up time of the generator 2 when the second connection scheme is executed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a power generation system. [Background technology]

[0002] Power generation systems equipped with automatic voltage regulators are known.

[0003] As a related technique, Patent Document 1 discloses an automatic voltage regulator for a synchronous generator or a brushless synchronous generator.

[0004] The automatic voltage regulator disclosed in Patent Document 1 suppresses overshoot during voltage establishment of the generator and prevents malfunction of the undervoltage relay. More specifically, the automatic voltage regulator disclosed in Patent Document 1 outputs a voltage command signal that increases the generator voltage to a target value in a ramp pattern from the point when the output signal of a timer measuring the time from the start of voltage establishment of the synchronous generator is 0 until the point when a first time setting value is reached, and then maintains that value thereafter. In this way, voltage overshoot during voltage establishment is suppressed regardless of the response speed of the synchronous generator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-304505 Summary of the Invention [Problem to be solved by the invention]

[0006] In the generator's automatic voltage regulator, the generator's output voltage is gradually increased to suppress the magnetizing inrush current of the transformer when power is turned on. Conventionally, the rate of increase in the generator's output voltage was set so that the magnetizing inrush current would not become excessive even in the worst case. This resulted in a long time required for the generator to start up.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power generation system that solves or improves the problems associated with the start-up time of the generator. [Means for solving the problem]

[0008] In order to solve the above problem, a power generation system in an embodiment of the present invention comprises a generator capable of supplying power to a power grid, an automatic voltage regulator that adjusts the output voltage of the generator, a transformer arranged between the power grid and the generator, a first circuit breaker that opens and closes a first current path between the transformer and the power grid, and a second circuit breaker that opens and closes a second current path between the generator and the transformer, and is capable of selectively executing a first connection method in which the second circuit breaker is changed from an open state to a closed state after the first circuit breaker is changed to a closed state, and a second connection method in which the first circuit breaker is changed from an open state to a closed state after the second circuit breaker is changed to a closed state, and is characterized in that the automatic voltage regulator makes the start-up time of the generator when the first connection method is executed shorter than the start-up time of the generator when the second connection method is executed.

[0009] Furthermore, a power generation system according to another embodiment of the present invention includes a generator capable of supplying power to a power grid, a second generator capable of supplying power to the power grid, an automatic voltage regulator that adjusts an output voltage of the generator, a second automatic voltage regulator that adjusts an output voltage of the second generator, a transformer disposed between the power grid, the generator, and the second generator, a first circuit breaker that opens and closes a first current path between the transformer and the power grid, a second circuit breaker that opens and closes a second current path between the generator and the transformer, and a third circuit breaker that opens and closes a third current path between the second generator and the transformer, and includes a first connection method in which the second circuit breaker is changed from an open state to a closed state after the first circuit breaker is changed to a closed state, and a second connection method in which the second circuit breaker is changed from an open state to a closed state after the second circuit breaker is closed. the automatic voltage regulator makes the start-up time of the generator when the first connection method is executed shorter than the start-up time of the generator when the second connection method is executed; the automatic voltage regulator is capable of selectively executing a third connection method in which the third circuit breaker is closed after the first circuit breaker is closed, and a fourth connection method in which the first circuit breaker is closed after the third circuit breaker is closed; and the automatic voltage regulator makes the start-up time of the second generator when the third connection method is executed shorter than the start-up time of the second generator when the fourth connection method is executed.Alternatively, a power generation system in another embodiment of the present invention includes a generator capable of supplying power to a load circuit, a second generator capable of supplying power to the load circuit, an automatic voltage regulator that adjusts an output voltage of the generator, a second automatic voltage regulator that adjusts an output voltage of the second generator, the load circuit, a transformer disposed between the generator and the second generator, a first circuit breaker that opens and closes a first current path between the transformer and the load circuit, a second circuit breaker that opens and closes a second current path between the generator and the transformer, and a third circuit breaker that opens and closes a third current path between the second generator and the transformer, and a fifth connection method in which the second circuit breaker is changed from an open state to a closed state while the third circuit breaker remains open, and a fifth connection method in which the third circuit breaker is changed from an open state to a closed state after the second circuit breaker is closed. a sixth connection method in which the second circuit breaker is changed from an open state to a closed state; a seventh connection method in which the second circuit breaker is kept in an open state and the third circuit breaker is changed from an open state to a closed state; and an eighth connection method in which the second circuit breaker is changed from an open state to a closed state after the third circuit breaker is changed to a closed state, wherein the second automatic voltage regulator controls the output voltage of the second generator so that a start-up time of the second generator when the sixth connection method is executed is shorter than a start-up time of the generator when the fifth connection method is executed, and the automatic voltage regulator controls the output voltage of the generator so that a start-up time of the generator when the eighth connection method is executed is shorter than a start-up time of the second generator when the seventh connection method is executed. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a power generation system that can solve or improve the problem related to the start-up time of the generator. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram schematically illustrating a power generation system according to the first embodiment. [Figure 2] FIG. 2 is a diagram schematically showing a state in which the first soft start time is relatively short when the first connection method is executed. [Figure 3] FIG. 3 is a diagram schematically showing a state in which the second soft start time is relatively long when the second connection method is executed. [Figure 4] FIG. 4 is a diagram schematically illustrating the power generation system according to the first embodiment. [Figure 5] FIG. 5 is a diagram schematically illustrating the power generation system according to the first embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating a power generation system according to the first embodiment. [Figure 7] FIG. 7 is a diagram schematically illustrating the power generation system according to the first embodiment. [Figure 8] FIG. 8 is a diagram schematically illustrating a power generation system according to the second embodiment. [Figure 9] FIG. 9 is a diagram schematically illustrating a power generation system according to the second embodiment. [Figure 10] FIG. 10 is a diagram schematically showing a state in which the first soft start time is relatively short when the first connection method is executed. [Figure 11] FIG. 11 is a diagram schematically showing a state in which the second soft start time is relatively long when the second connection method is executed. [Figure 12] FIG. 12 is a diagram schematically illustrating a power generation system according to the second embodiment. [Figure 13] FIG. 13 is a diagram schematically illustrating a power generation system according to the second embodiment. [Figure 14] FIG. 14 is a diagram schematically illustrating a power generation system according to the third embodiment. [Figure 15] FIG. 15 is a diagram schematically showing a state in which the third soft start time is relatively short when the third connection method is executed. [Figure 16] FIG. 16 is a diagram schematically showing a state in which the fourth soft start time is relatively long when the fourth connection method is executed. [Figure 17] FIG. 17 is a diagram schematically illustrating a power generation system according to the third embodiment. [Figure 18]FIG. 18 is a diagram schematically illustrating a power generation system according to the third embodiment. [Figure 19] FIG. 19 is a diagram schematically illustrating a power generation system according to the third embodiment. [Figure 20] FIG. 20 is a diagram schematically illustrating a power generation system according to a modified example of the third embodiment. [Figure 21] FIG. 21 is a diagram schematically illustrating a power generation system according to the fourth embodiment. [Figure 22] FIG. 22 is a diagram schematically illustrating a power generation system according to the fourth embodiment. [Figure 23] FIG. 23 is a diagram schematically showing a state in which the fourth soft start time is relatively long when the fourth connection method is executed. DETAILED DESCRIPTION OF THE INVENTION

[0012] The power generation system 1 according to the embodiment will be described below with reference to the accompanying drawings. In the following description, the same reference numerals are used to designate components and parts having the same functions, and repeated description of the same reference numerals will be omitted.

[0013] (First embodiment) A power generation system 1A according to a first embodiment will be described with reference to Figs. 1 to 7. Fig. 1 is a diagram schematically showing the power generation system 1A according to the first embodiment. Fig. 2 is a diagram schematically showing a state in which the first soft start time T1 is relatively short when the first connection method C1 is implemented. Fig. 3 is a diagram schematically showing a state in which the second soft start time T2 is relatively long when the second connection method C2 is implemented. Figs. 4 and 5 are diagrams schematically showing the power generation system 1A according to the first embodiment. Figs. 6 and 7 are diagrams schematically showing the power generation system 1A according to the first embodiment.

[0014] (Composition / effect) 1, a power generation system 1A in the first embodiment includes a generator 2, an automatic voltage regulator 3, a transformer 4, a first circuit breaker 51, and a second circuit breaker 56. In the example shown in FIG. 1, the power generation system 1A includes an exciter 11. The power generation system 1A may also include a switching unit 6.

[0015] The generator 2 is a machine that generates AC power using the principle of electromagnetic induction. The generator 2 converts rotational energy generated by a prime mover 101 (e.g., an engine) into electrical energy. The generator 2 supplies power to a power grid 111 (e.g., a commercial power grid).

[0016] In the example shown in FIG. 1, the generator 2 is connected to the power grid 111 and can supply power to any load (e.g., electrical equipment). The generator 2 may be any type of generator. For example, the generator 2 is a synchronous generator, that is, an AC generator that generates power in synchronization with the rotational speed at which the magnetic field created by the field magnet crosses the armature winding. The generator 2 is, for example, a brushless synchronous generator.

[0017] 1, the generator 2 is driven by a prime mover 101. The generator 2 is also connected to an electric power grid 111 via a second circuit breaker 56, a transformer 4, and a first circuit breaker 51, and supplies electric power to any load via the electric power grid 111.

[0018] The exciter 11 is a rotating machine for supplying an excitation current to the field of the generator 2. The exciter 11 may be of any type. In the example shown in Fig. 1, the rotor of the generator 2 and the rotor of the exciter 11 are arranged coaxially.

[0019] The automatic voltage regulator 3 adjusts the output voltage of the generator 2. The automatic voltage regulator 3 is a control device that can control the excitation current of the generator 2 or the exciter 11 so that the output voltage of the generator 2 is kept constant during steady-state operation of the generator 2. The automatic voltage regulator 3 may be realized by hardware (in other words, physical components, for example, electronic circuits) or by software executed on a computer, or some of the components of the automatic voltage regulator 3 may be realized by hardware and other parts of the components of the automatic voltage regulator 3 may be realized by software.

[0020] 2 and 3 each show an example of the change over time in the voltage command value Vg of the automatic voltage regulator 3 when starting up the generator 2. In the example shown in Fig. 2 and Fig. 3, when starting up the generator 2, the output voltage of the generator 2 increases in accordance with the voltage command value Vg of the automatic voltage regulator 3.

[0021] In this specification, "soft start" is defined as gradually increasing the output voltage of a generator from zero to the rated voltage of the generator (e.g., rated voltage V1) when the generator is started up, and "soft start time" is defined as the time it takes for the output voltage of the generator to reach the rated voltage of the generator (e.g., rated voltage V1) from zero when the generator is started up. In the examples shown in FIGS. 2 and 3, the soft start time is switchable. More specifically, when the generator 2 is started up, the soft start time it takes for the output voltage of the generator 2 to reach the rated voltage V1 from zero is switchable between at least a first soft start time T1 (see FIG. 2) and a second soft start time T2 (see FIG. 3).

[0022] 1, the transformer 4 is disposed between the power grid 111 and the generator 2. The transformer 4 converts the output voltage of the generator 2 into a voltage suitable for the power grid 111 (or any load connected to the power grid 111). The transformer 4 is an isolation transformer in which the primary winding and the secondary winding are insulated from each other.

[0023] The first circuit breaker 51 opens and closes a first current path L1 between the transformer 4 and the power grid 111. In the example shown in FIG. 1 , the power generation system 1A has a first current path L1 connecting the transformer 4 and the power grid 111, and the first circuit breaker 51 is disposed on the first current path L1. When the first circuit breaker 51 is in an open state, the connection between the power grid 111 and the transformer 4 is interrupted. The first circuit breaker 51 can interrupt the current flowing through the first current path L1 by switching the first circuit breaker 51 from a closed state to an open state, regardless of whether a load current or a fault current (in other words, a large current) is flowing through the first current path L1. The first circuit breaker 51 is, for example, a vacuum circuit breaker.

[0024] The second circuit breaker 56 opens and closes the second current path L2 between the generator 2 and the transformer 4. In the example shown in FIG. 1 , the power generation system 1A has the second current path L2 connecting the generator 2 and the transformer 4, and the second circuit breaker 56 is disposed on the second current path L2. When the second circuit breaker 56 is in an open state, the connection between the generator 2 and the transformer 4 is interrupted. The second circuit breaker 56 can interrupt the current flowing through the second current path L2 by switching the second circuit breaker 56 from a closed state to an open state, regardless of whether a load current or a fault current (in other words, a large current) is flowing through the second current path L2. The second circuit breaker 56 is, for example, a vacuum circuit breaker.

[0025] As illustrated in Figures 4 and 5, the power generation system 1A in the first embodiment can selectively execute a first connection method C1 (see Figure 4) in which the second circuit breaker 56 is changed from an open state to a closed state after the first circuit breaker 51 is changed to a closed state, and a second connection method C2 (see Figure 5) in which the first circuit breaker 51 is changed from an open state to a closed state after the second circuit breaker 56 is changed to a closed state.

[0026] As illustrated in Figures 2 and 3, the automatic voltage regulator 3 makes the start-up time of the generator 2 when the first connection method C1 (see Figure 4) is executed (more specifically, the first soft-start time T1 in Figure 2) shorter than the start-up time of the generator 2 when the second connection method C2 (see Figure 5) is executed (more specifically, the second soft-start time T2 in Figure 3).

[0027] More specifically, the automatic voltage regulator 3 controls the excitation current of the generator 2 or the exciter 11 so that the start-up time of the generator 2 when the first connection method C1 (see FIG. 4) is executed (more specifically, the first soft start time T1 in FIG. 2) is shorter than the start-up time of the generator 2 when the second connection method C2 (see FIG. 5) is executed (more specifically, the second soft start time T2 in FIG. 3).

[0028] (effect) The power generation system 1A in the first embodiment can implement a first connection method C1 (see FIG. 4 ) in which the second circuit breaker 56 is changed from an open state to a closed state after the first circuit breaker 51 is changed to a closed state. As illustrated in FIG. 4 , when the transformer 4 is connected from the power grid 111 side and excited, the start-up time of the generator 2 is set to a relatively short time (more specifically, a first soft-start time T1) (see setting A in FIG. 2 ) because power is supplied from the infinite bus (power grid 111) (there is no need to consider voltage drop, etc.). The first soft-start time T1 is, for example, about 2 seconds.

[0029] The power generation system 1A in the first embodiment can implement a second connection method C2 (see FIG. 5) in which the first circuit breaker 51 is changed from an open state to a closed state after the second circuit breaker 56 is changed to a closed state. As illustrated in FIG. 5, when the transformer 4 is connected from the generator 2 side to excite the transformer 4, the start-up time of the generator 2 is set to a relatively long time (more specifically, a second soft-start time T2) in order to suppress the magnetizing inrush current of the transformer 4 and to more gradually increase the output voltage of the generator 2 (see setting B in FIG. 3). The second soft-start time T2 is, for example, about 1 to 2 minutes.

[0030] As described above, the first embodiment provides a power generation system 1A that can solve or improve problems related to the start-up time of the generator 2. More specifically, when the power source that excites the transformer 4 is the power grid 111, the start-up time of the generator 2 is set to a shorter time, and when the power source that excites the transformer 4 is the generator 2, the start-up time of the generator 2 is set to a longer time to prevent the magnetizing inrush current of the transformer 4 from adversely affecting peripheral circuits.

[0031] Next, optional additional configurations that can be adopted in the first embodiment will be described.

[0032] (Switching unit 6) 4 and 5, the switching unit 6 receives a first state signal S1 indicating whether the first circuit breaker 51 is in a closed state or an open state, and a second state signal S2 indicating whether the second circuit breaker 56 is in a closed state or an open state. In addition, the switching unit 6 switches the control mode used by the automatic voltage regulator 3 when starting up the generator 2 between a first control mode M1 (see FIG. 2) in which the start-up time of the generator 2 is relatively short, and a second control mode M2 ​​(see FIG. 3) in which the start-up time of the generator 2 is relatively long, in accordance with the first state signal S1 and the second state signal S2.

[0033] 2 and 4, when the first state signal S1 indicates the closed state and the second state signal S2 indicates the open state (see FIG. 4), the switching unit 6 switches the control mode to the first control mode M1 (see FIG. 2). On the other hand, when the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state (see FIG. 5), as illustrated in FIGS. 3 and 5, the switching unit 6 switches the control mode to the second control mode M2 ​​(see FIG. 3).

[0034] The switching unit 6 may be configured by hardware or by software running on a computer. The switching unit 6 may be provided separately from the automatic voltage regulator 3, or may be included in the automatic voltage regulator 3.

[0035] In the example shown in FIGS. 4 and 5, the switching unit 6 is a switch 6a that can output a switching signal.

[0036] 4 and 5, the switch 6a receives a first state signal S1 indicating whether the first circuit breaker 51 is in a closed state or an open state, and a second state signal S2 indicating whether the second circuit breaker 56 is in a closed state or an open state. In addition, the switch 6a switches the control mode used by the automatic voltage regulator 3 when starting up the generator 2 between a first control mode M1 (see FIG. 2) in which the start-up time of the generator 2 is relatively short, and a second control mode M2 ​​(see FIG. 3) in which the start-up time of the generator 2 is relatively long, in accordance with the first state signal S1 and the second state signal S2.

[0037] As illustrated in Fig. 4, when the first state signal S1 indicates the closed state and the second state signal S2 indicates the open state, the switch 6a outputs a first switching signal E1 to the automatic voltage regulator 3. When the automatic voltage regulator 3 receives the first switching signal E1, it executes the first control mode M1 (see Fig. 2). On the other hand, as illustrated in Fig. 5, when the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state, the switch 6a outputs a second switching signal E2 to the automatic voltage regulator 3. When the automatic voltage regulator 3 receives the second switching signal E2, it executes the second control mode M2 ​​(see Fig. 3).

[0038] Alternatively, the output of the second switching signal E2 may be omitted. More specifically, when the automatic voltage regulator 3 does not receive the first switching signal E1 from the switch 6a, the second control mode M2 ​​(see FIG. 3) may be executed. In this case, the control mode at start-up of the generator 2 in the default state is the second control mode M2, and when the automatic voltage regulator 3 receives the first switching signal E1 from the switch 6a, the automatic voltage regulator 3 is configured to execute the first control mode M1 as the control mode at start-up of the generator 2.

[0039] When the power generation system 1A has the switching unit 6 (or the switch 6a), the control mode at the start-up of the generator 2 by the automatic voltage regulator 3 is appropriately switched between the first control mode M1 and the second control mode M2 ​​depending on the state of the first circuit breaker 51 and the state of the second circuit breaker 56. This prevents erroneous mode selection.

[0040] (Automatic Voltage Regulator 3) The automatic voltage regulator 3 adjusts the output voltage of the generator 2. For example, the automatic voltage regulator 3 controls the output voltage of the generator 2 by adjusting the excitation current flowing from a power source such as a DC power supply 13 to the exciter 11 (or the excitation current flowing to the field winding 22 of the generator 2). The DC power supply 13 may include, for example, a permanent magnet generator and a rectifier connected to its output terminals, or may include a circuit that rectifies the voltage of the generator 2 with the rectifier, or may be configured with other mechanisms.

[0041] In the example shown in FIG. 2, when the first control mode M1 is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along a first gradual increase line F1. In the example shown in FIG. 3, when the second control mode M2 ​​is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along a second gradual increase line F2. The slope of the first gradual increase line F1 (in other words, the rate of increase of the voltage command value Vg when the first control mode M1 is executed) is greater than the slope of the second gradual increase line F2 (in other words, the rate of increase of the voltage command value Vg when the second control mode M2 ​​is executed). Therefore, the ramp-up time of the generator 2 when the first control mode M1 is executed is shorter than the ramp-up time of the generator 2 when the second control mode M2 ​​is executed. In the examples shown in FIGS. 2 and 3, the slopes of the first gradual increase line F1 and the second gradual increase line F2 are constant. Alternatively, the slope of each of the first increasing line F1 and the second increasing line F2 may be configured to change continuously or stepwise.

[0042] In the examples shown in FIGS. 6 and 7, the automatic voltage regulator 3 has a command value output unit 31 that outputs a voltage command value Vg.

[0043] As illustrated in FIG. 6, when the first state signal S1 indicates the closed state and the second state signal S2 indicates the open state (more specifically, when the automatic voltage regulator 3 receives the first switching signal E1 from the switch 6a), the command value output unit 31 outputs a voltage command value Vg that increases over time along the first gradual increase line F1 (see FIG. 2).

[0044] On the other hand, as illustrated in FIG. 7, when the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state (more specifically, when the automatic voltage regulator 3 receives the second switching signal E2 from the switch 6a), the command value output unit 31 outputs a voltage command value Vg that increases over time along the second gradual increase line F2 (see FIG. 3).

[0045] Alternatively, the output of the second switching signal E2 may be omitted. More specifically, when the automatic voltage regulator 3 does not receive the first switching signal E1 from the switch 6a, the command value output unit 31 may output a voltage command value Vg that increases over time along the second gradual increase line F2 (see FIG. 3 ). In this case, the control mode at start-up of the generator 2 in the default state is the second control mode M2, and when the automatic voltage regulator 3 receives the first switching signal E1 from the switch 6a, the automatic voltage regulator 3 is configured to execute the first control mode M1 as the control mode at start-up of the generator 2.

[0046] 6 and 7, the power generation system 1A includes a voltage detector 71. The automatic voltage regulator 3 also includes a command value output unit 31 and a first calculation unit 33.

[0047] The voltage detector 71 detects the output voltage of the generator 2 and outputs a voltage detection value Va corresponding to the detected output voltage.

[0048] The first calculation unit 33 performs calculation based on at least the voltage command value Vg and the voltage detection value Va, and outputs an operation signal for controlling the field current flowing through the field winding of the exciter 11. The first calculation unit 33 also outputs the operation signal to the pulse signal generator 35. The pulse signal generator 35 outputs a pulse signal for chopping the DC voltage of the DC power supply 13 based on the operation signal. The chopper device 36 chops the DC voltage of the DC power supply 13 based on the pulse signal from the pulse signal generator 35.

[0049] (Procedure for connecting the generator 2 to the power grid 111 using the first connection method C1) As illustrated in Fig. 4 (or Fig. 6), first, the first circuit breaker 51 is closed and the second circuit breaker 56 is opened. The fact that the first circuit breaker 51 is closed and the second circuit breaker 56 is opened is detected by the switching unit 6 (more specifically, the switch 6a).

[0050] Second, the automatic voltage regulator 3 performs start-up control of the generator 2. More specifically, when the switching unit 6 detects that the first circuit breaker 51 has been closed and the second circuit breaker 56 has been opened, the automatic voltage regulator 3 executes the first control mode M1 (more specifically, the first control mode M1 in which the start-up time of the generator 2 is relatively short) as the control mode for start-up of the generator 2. When the first control mode M1 is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along the first gradual increase line F1 (see FIG. 2 ).

[0051] Third, by executing the first control mode M1, the second circuit breaker 56 is switched from the open state to the closed state after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1). Switching the second circuit breaker 56 from the open state to the closed state is performed, for example, by a control device 79 (see FIG. 6) that controls equipment including the second circuit breaker 56.

[0052] More specifically, after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1), the control device 79 automatically switches the second circuit breaker 56 from an open state to a closed state. In this way, the generator 2 is connected to the power grid 111. Alternatively, the second circuit breaker 56 may be switched from an open state to a closed state by manual operation.

[0053] (Procedure for connecting the generator 2 to the power grid 111 using the second connection method C2) As illustrated in Fig. 5 (or Fig. 7), first, the first circuit breaker 51 is opened and the second circuit breaker 56 is closed. The fact that the first circuit breaker 51 is opened and the second circuit breaker 56 is closed is detected by the switching unit 6 (more specifically, the switch 6a).

[0054] Second, the automatic voltage regulator 3 performs start-up control of the generator 2. More specifically, when the switching unit 6 detects that the first circuit breaker 51 has been opened and the second circuit breaker 56 has been closed, the automatic voltage regulator 3 executes the second control mode M2 ​​(more specifically, the second control mode M2 ​​in which the start-up time of the generator is relatively long) as the control mode for start-up of the generator 2. When the second control mode M2 ​​is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along the second gradual increase line F2 (see FIG. 3 ).

[0055] Third, by executing the second control mode M2, the first circuit breaker 51 is switched from the open state to the closed state after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1). Switching of the first circuit breaker 51 from the open state to the closed state is performed, for example, by a control device 79 (see FIG. 7) that controls equipment including the first circuit breaker 51.

[0056] More specifically, after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1), the control device 79 automatically switches the first circuit breaker 51 from an open state to a closed state. In this way, the generator 2 is connected to the power grid 111. Alternatively, the first circuit breaker 51 may be switched from an open state to a closed state by manual operation.

[0057] (Second embodiment) A power generation system 1B according to the second embodiment will be described with reference to Fig. 8 to Fig. 13. Fig. 8 and Fig. 9 are diagrams that schematically show the power generation system 1B according to the second embodiment. Fig. 10 is a diagram that schematically shows a state in which the first soft start time T1 is relatively short when the first connection method C1 is implemented. Fig. 11 is a diagram that schematically shows a state in which the second soft start time T2 is relatively long when the second connection method C2 is implemented. Figs. 12 and 13 are diagrams that schematically show the power generation system 1B according to the second embodiment.

[0058] (Composition / effect) The power generation system 1B in the second embodiment differs from the power generation system 1A in the first embodiment in that it includes a current detector 76 and accelerates the rate of increase in the output voltage of the generator 2 after the magnetizing inrush current of the transformer subsides.

[0059] In the second embodiment, differences from the first embodiment will be mainly described, and a repetitive description of matters already described in the first embodiment will be omitted. Therefore, it goes without saying that matters already described in the first embodiment can be adopted in the second embodiment even if they are not explicitly described in the second embodiment.

[0060] As illustrated in Fig. 8, a power generation system 1B in the second embodiment includes a generator 2, an automatic voltage regulator 3, a transformer 4, a first circuit breaker 51, and a second circuit breaker 56. Additionally, as illustrated in Fig. 12, the power generation system 1B may include a switching unit 6 (more specifically, a switching unit 6a), an exciter 11, a DC power supply 13, a voltage detector 71, and a control device 79. The generator 2, the automatic voltage regulator 3, the transformer 4, the first circuit breaker 51, the second circuit breaker 56, the exciter 11, the DC power supply 13, the voltage detector 71, and the control device 79 have already been described in the first embodiment, and therefore repeated description of these components will be omitted.

[0061] 8, the power generation system 1B includes a current detector 76. The current detector 76 detects the output current of the generator 2. More specifically, the current detector 76 detects the current flowing through the second current path L2 between the generator 2 and the transformer 4.

[0062] As illustrated in Figure 9, when the second connection method C2 is executed (in other words, when the transformer 4 is connected from the generator 2 side and excited), the automatic voltage regulator 3 accelerates the rate of increase of the output voltage of the generator 2 after the excitation inrush current of the transformer 4 subsides (see Figure 11).

[0063] (effect) The second embodiment achieves the same effects as the first embodiment. More specifically, the power generation system 1B in the second embodiment can implement a first connection method C1 (see FIG. 8 ) in which the second circuit breaker 56 is changed from an open state to a closed state after the first circuit breaker 51 is changed to a closed state. As illustrated in FIG. 8 , when the transformer 4 is connected from the power grid 111 side and excited, the start-up time of the generator 2 is set to a relatively short time (more specifically, a first soft-start time T1) because power is supplied from the infinite bus (power grid 111) (because there is no need to consider voltage drop, etc.) (see setting A in FIG. 10 ). Furthermore, the power generation system 1B in the second embodiment can implement a second connection method C2 (see FIG. 9 ) in which the first circuit breaker 51 is changed from an open state to a closed state after the second circuit breaker 56 is changed to a closed state. As illustrated in Figure 9, when the transformer 4 is connected from the generator 2 side and excited, in order to suppress the excitation inrush current of the transformer 4, the start-up time of the generator 2 is set to a relatively long time (more specifically, the second soft start time T2) so as to more gradually increase the output voltage of the generator 2 (see setting B in the upper diagram in Figure 11).

[0064] Furthermore, in the second embodiment, when the transformer 4 is connected from the generator 2 side and excited, the rate of increase in the output voltage of the generator 2 is accelerated after the excitation inrush current of the transformer 4 subsides (see the lower diagram in FIG. 11). Therefore, when the transformer 4 is connected from the generator 2 side and excited (see FIG. 9), the start-up time of the generator 2 can be shortened.

[0065] Next, optional additional configurations that can be adopted in the second embodiment will be described.

[0066] (Switching unit 6) 8 and 9, the switching unit 6 (more specifically, the switch 6a) receives a first state signal S1 indicating whether the first circuit breaker 51 is in a closed state or an open state, and a second state signal S2 indicating whether the second circuit breaker 56 is in a closed state or an open state. In addition, the switching unit 6 (more specifically, the switch 6a) switches the control mode used by the automatic voltage regulator 3 during start-up of the generator 2 between a first control mode M1 (see FIG. 10) in which the start-up time of the generator 2 is relatively short, and a second control mode M2 ​​(see FIG. 11) in which the start-up time of the generator 2 is relatively long, in accordance with the first state signal S1 and the second state signal S2.

[0067] The switching unit 6 (more specifically, the switch 6a) and the first control mode M1 have already been described in the first embodiment, so a repeated description of these components will be omitted.

[0068] (Second control mode M2) As illustrated in FIGS. 9 and 11, when the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state (see FIG. 9), the switching unit 6 switches the above-mentioned control mode to the second control mode M2.

[0069] More specifically, when the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state (see FIG. 9), the switch 6a outputs a second switching signal E2 to the automatic voltage regulator 3. When the automatic voltage regulator 3 receives the second switching signal E2, it executes the second control mode M2.

[0070] Alternatively, the output of the second switching signal E2 may be omitted. More specifically, when the automatic voltage regulator 3 does not receive the first switching signal E1 (see FIG. 8) from the switch 6a, the automatic voltage regulator 3 may execute the second control mode M2.

[0071] When the first state signal S1 indicates the open state and the second state signal S2 indicates the closed state (more specifically, when the automatic voltage regulator 3 receives the second switching signal E2 from the switch 6a, or when the automatic voltage regulator 3 does not receive the first switching signal E1 from the switch 6a), the automatic voltage regulator 3 (more specifically, the command value output unit 31 shown in FIG. 13) outputs a voltage command value Vg that increases over time along the second gradual increase line F2 (see the upper diagram in FIG. 11).

[0072] 11, when it is determined that the magnetizing inrush current of the transformer 4 has subsided based on the output current of the generator 2 detected by the current detector 76, the automatic voltage regulator 3 accelerates the rate of increase of the output voltage of the generator 2. This determination is made by, for example, the automatic voltage regulator 3.

[0073] More specifically, when the output current of the generator 2 detected by the current detector 76 increases beyond a preset first threshold value TH1 and then falls below the first threshold value TH1, it is determined that the magnetizing inrush current has subsided. Furthermore, when it is determined that the magnetizing inrush current of the transformer 4 has subsided, the automatic voltage regulator 3 accelerates the rate of increase of the output voltage of the generator 2.

[0074] More specifically, when the second connection method C2 or the second control mode M2 ​​is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along the second gradual increase line F2, and when it is determined that the excitation inrush current has subsided during execution of the second connection method C2 or the second control mode M2, the automatic voltage regulator 3 increases the slope of the second gradual increase line F2, which indicates the rate of increase of the voltage command value Vg for adjusting the output voltage of the generator 2.

[0075] 11, the slope of the second gradual increase line F2 at a time point after the first time TM at which it is determined that the magnetizing inrush current has subsided (for example, a time point immediately after the first time TM) is greater than the slope of the second gradual increase line F2 at a time point before the first time TM at which it is determined that the magnetizing inrush current has subsided (for example, a time point immediately before the first time TM). In the examples shown in FIGS. 10 and 11, the slope of the second gradual increase line F2 at a time point after the first time TM at which it is determined that the magnetizing inrush current has subsided is substantially equal to the slope of the first gradual increase line F1 (in other words, the slope of the first gradual increase line F1 indicating the increase rate of the voltage command value Vg when the first control mode M1 is executed).

[0076] (Automatic Voltage Regulator 3) The automatic voltage regulator 3 adjusts the output voltage of the generator 2. In the example shown in Fig. 12, the automatic voltage regulator 3 has a command value output unit 31, a first calculation unit 33, a pulse signal generator 35, and a chopper device 36. The command value output unit 31, the first calculation unit 33, the pulse signal generator 35, and the chopper device 36 have already been described in the first embodiment, so repeated description of these components will be omitted.

[0077] (Procedure for connecting the generator 2 to the power grid 111 using the first connection method C1) The procedure for connecting the generator 2 to the power grid 111 using the first connection method C1 is the same as in the first embodiment, so a repeated description of the connection procedure will be omitted.

[0078] (Procedure for connecting the generator 2 to the power grid 111 using the second connection method C2) As illustrated in Fig. 9 (or Fig. 13), first, the first circuit breaker 51 is opened and the second circuit breaker 56 is closed. The fact that the first circuit breaker 51 is opened and the second circuit breaker 56 is closed is detected by the switching unit 6 (more specifically, the switch 6a).

[0079] Second, the automatic voltage regulator 3 performs start-up control of the generator 2. More specifically, when the switching unit 6 detects that the first circuit breaker 51 has been opened and the second circuit breaker 56 has been closed, the automatic voltage regulator 3 executes the second control mode M2 ​​(more specifically, the second control mode M2 ​​in which the start-up time of the generator is relatively long) as the control mode for start-up of the generator 2. When the second control mode M2 ​​is executed, the automatic voltage regulator 3 increases the voltage command value Vg for adjusting the output voltage of the generator 2 over time along the second gradual increase line F2, and after the magnetizing inrush current of the transformer 4 subsides, the automatic voltage regulator 3 accelerates the increase rate of the output voltage of the generator 2 (more specifically, as illustrated in FIG. 11 , increases the slope of the second gradual increase line F2, which indicates the increase rate of the voltage command value Vg for adjusting the output voltage of the generator 2).

[0080] Third, by executing the second control mode M2, the first circuit breaker 51 is switched from the open state to the closed state after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1). Switching of the first circuit breaker 51 from the open state to the closed state is performed by, for example, the control device 79 that controls the equipment including the first circuit breaker 51.

[0081] More specifically, after the output voltage of the generator 2 reaches a predetermined voltage (more specifically, the rated voltage V1), the control device 79 automatically switches the first circuit breaker 51 from an open state to a closed state. In this way, the generator 2 is connected to the power grid 111. Alternatively, the first circuit breaker 51 may be switched from an open state to a closed state by manual operation.

[0082] (Third embodiment) A power generation system 1C according to the third embodiment will be described with reference to Figs. 14 to 20. Fig. 14 is a diagram schematically illustrating the power generation system 1C according to the third embodiment. Fig. 15 is a diagram schematically illustrating a state in which the third soft start time T3 is relatively short when the third connection method C3 is implemented. Fig. 16 is a diagram schematically illustrating a state in which the fourth soft start time T4 is relatively long when the fourth connection method C4 is implemented. Figs. 17 to 19 are diagrams schematically illustrating the power generation system 1C according to the third embodiment. Fig. 20 is a diagram schematically illustrating the power generation system 1C according to a modified example of the third embodiment.

[0083] (Composition / effect) The power generation system 1C of the third embodiment differs from the power generation system 1A of the first embodiment in that it includes a second generator 2-2, a second automatic voltage regulator 3-2, and a third circuit breaker 56-2. In other respects, the power generation system 1C of the third embodiment is similar to the power generation system 1A of the first embodiment.

[0084] In the third embodiment, differences from the first embodiment will be mainly described, and a repetitive description of matters already described in the first embodiment will be omitted. Therefore, it goes without saying that matters already described in the first embodiment can be adopted in the third embodiment even if they are not explicitly described in the third embodiment.

[0085] 14, a power generation system 1C in the third embodiment includes a generator 2, an automatic voltage regulator 3, a transformer 4, a first circuit breaker 51, a second circuit breaker 56, a second generator 2-2, a second automatic voltage regulator 3-2, and a third circuit breaker 56-2. Additionally, the power generation system 1C may include a switching unit 6 (more specifically, a switching unit 6a), an exciter 11, a DC power supply 13, a voltage detector 71, and a control device 79. The generator 2, the automatic voltage regulator 3, the transformer 4, the first circuit breaker 51, the second circuit breaker 56, the exciter 11, the DC power supply 13, the voltage detector 71, and the control device 79 have already been described in the first embodiment, and therefore, repeated description of these components will be omitted.

[0086] The second generator 2-2 supplies power to a power grid 111 (for example, a commercial power grid). In the example shown in FIG. 14, the second generator 2-2 is interconnected with the power grid 111 (for example, a commercial power grid) and can supply power to any load (for example, an electrical device). The second generator 2-2 may be any type of generator. In the example shown in FIG. 14, the second generator 2-2 is driven by a second prime mover 101-2. The second generator 2-2 is also interconnected with the power grid 111 via a third circuit breaker 56-2, a transformer 4, and a first circuit breaker 51, and supplies power to any load via the power grid 111.

[0087] The second automatic voltage regulator 3-2 adjusts the output voltage of the second generator 2-2. The second automatic voltage regulator 3-2 has, for example, the same configuration as the automatic voltage regulator 3 described above.

[0088] 15 and 16 each show an example of the change over time in the voltage command value Vg-2 of the second automatic voltage regulator 3-2 when the second generator 2-2 starts up. In the examples shown in Fig. 15 and 16, when the second generator 2-2 starts up, the output voltage of the second generator 2-2 increases in accordance with the voltage command value Vg-2 of the second automatic voltage regulator 3-2.

[0089] 15 and 16, the soft start time can be switched. More specifically, when starting up the second generator 2-2, the soft start time required for the output voltage of the second generator 2-2 to reach the rated voltage V1-2 from zero can be switched between at least a third soft start time T3 (see setting C in FIG. 15) and a fourth soft start time T4 (see setting D in FIG. 16).

[0090] The third circuit breaker 56-2 opens and closes the third current path L3 between the second generator 2-2 and the transformer 4. In the example shown in FIG. 14 , the power generation system 1C includes the third current path L3 connecting the second generator 2-2 and the transformer 4, and the third circuit breaker 56-2 is disposed on the third current path L3. When the third circuit breaker 56-2 is in the open state, the connection between the second generator 2-2 and the transformer 4 is interrupted. Regardless of whether a load current or a fault current (in other words, a large current) is flowing through the third current path L3, the third circuit breaker 56-2 can interrupt the current flowing through the third current path L3 by switching the third circuit breaker 56-2 from the closed state to the open state.

[0091] As illustrated in Figures 17 and 18, the power generation system 1C in the third embodiment can selectively execute a third connection method C3 (see Figure 17) in which the third circuit breaker 56-2 is changed from an open state to a closed state after the first circuit breaker 51 is changed to a closed state, and a fourth connection method C4 (see Figure 18) in which the first circuit breaker 51 is changed from an open state to a closed state after the third circuit breaker 56-2 is changed to a closed state.

[0092] As illustrated in Figures 17 and 18, the automatic voltage regulator 3 makes the start-up time of the second generator 2-2 when the third connection method C3 (see Figure 17) is executed (more specifically, the third soft start time T3 in Figure 15) shorter than the start-up time of the second generator 2-2 when the fourth connection method C4 (see Figure 18) is executed (more specifically, the fourth soft start time T4 in Figure 16).

[0093] More specifically, the second automatic voltage regulator 3-2 controls the excitation current of the second generator 2-2 or the second exciter 11-2 so that the start-up time of the second generator 2-2 when the third connection method C3 (see Figure 17) is executed (more specifically, the third soft start time T3 in Figure 15) is shorter than the start-up time of the second generator 2-2 when the fourth connection method C4 (see Figure 18) is executed (more specifically, the fourth soft start time T4 in Figure 16).

[0094] (effect) The third embodiment has the same effects as the first embodiment. Furthermore, in the third embodiment, the generator 2 and the second generator 2-2 can each supply power to the power grid 111 via the transformer 4. This ensures system redundancy, or strengthens the supply of power to the power grid 111. Furthermore, the third embodiment can provide a power generation system that can solve or improve the problem related to the start-up time of the second generator 2-2.

[0095] Next, optional additional configurations that can be adopted in the third embodiment will be described.

[0096] (Switching unit 6) In the examples shown in Figures 17 to 19, the switching unit 6 (more specifically, the switch 6a) receives a first state signal S1 indicating whether the first circuit breaker 51 is in a closed state or an open state, a second state signal S2 indicating whether the second circuit breaker 56 is in a closed state or an open state, and a third state signal S3 indicating whether the third circuit breaker 56-2 is in a closed state or an open state.

[0097] 17 to 19, the switching unit 6 (more specifically, the switch 6a) switches the control mode used by the automatic voltage regulator 3 to start up the generator 2 between a first control mode M1 (see FIG. 2) in which the start-up time of the generator 2 is relatively short and a second control mode M2 ​​(see FIG. 3) in which the start-up time of the generator 2 is relatively long, in response to the first state signal S1, the second state signal S2, and the third state signal S3. The switching unit 6 (more specifically, the switch 6a) also switches the control mode used by the second automatic voltage regulator 3-2 to start up the second generator 2-2 between a third control mode M3 (see FIG. 15) in which the start-up time of the second generator 2-2 is relatively short and a fourth control mode M4 (see FIG. 16) in which the start-up time of the second generator 2-2 is relatively long, in response to the first state signal S1, the second state signal S2, and the third state signal S3.

[0098] As illustrated in Figure 17, when the first status signal S1 is a signal indicating that the first circuit breaker 51 is in a closed state, the switching unit 6 (more specifically, the switch 6a) switches the control mode used by the automatic voltage regulator 3 to start up the generator 2 to the first control mode M1 (see Figure 2), in which the start-up time of the generator 2 is relatively short, and switches the control mode used by the second automatic voltage regulator 3-2 to start up the second generator 2-2 to the third control mode M3 (see Figure 15), in which the start-up time of the second generator 2-2 is relatively short.

[0099] 17, the automatic voltage regulator 3 executes the first control mode M1 (see FIG. 2) as the control mode when the automatic voltage regulator 3 starts up the generator 2, based on the output from the switching unit 6 (more specifically, the switch 6a). Furthermore, the second automatic voltage regulator 3-2 executes the third control mode M3 (see FIG. 15) as the control mode when the second automatic voltage regulator 3-2 starts up the second generator 2-2, based on the output from the switching unit 6 (more specifically, the switch 6a).

[0100] As illustrated in Figure 18, when the first state signal S1 is a signal indicating that the first circuit breaker 51 is in an open state, the second state signal S2 is a signal indicating that the second circuit breaker 56 is in an open state, and the third state signal S3 is a signal indicating that the third circuit breaker 56-2 is in a closed state, the switching unit 6 (more specifically, the switch 6a) switches the control mode when the automatic voltage regulator 3 starts up the generator 2 to the first control mode M1 (see Figure 2) in which the start-up time of the generator 2 is relatively short, and switches the control mode when the second automatic voltage regulator 3-2 starts up the second generator 2-2 to the fourth control mode M4 (see Figure 16) in which the start-up time of the second generator 2-2 is relatively long.

[0101] In the example shown in FIG. 18, the second automatic voltage regulator 3-2 executes the fourth control mode M4 (see FIG. 16) as the control mode when the second automatic voltage regulator 3-2 starts up the second generator 2-2, based on the output from the switching unit 6 (more specifically, the switching unit 6a).

[0102] As illustrated in Figure 19, when the first state signal S1 is a signal indicating that the first circuit breaker 51 is in an open state, the second state signal S2 is a signal indicating that the second circuit breaker 56 is in a closed state, and the third state signal S3 is a signal indicating that the third circuit breaker 56-2 is in an open state, the switching unit 6 (more specifically, the switch 6a) switches the control mode used by the automatic voltage regulator 3 to start up the generator 2 to the second control mode M2 ​​(see Figure 3) in which the start-up time of the generator 2 is relatively long, and switches the control mode used by the second automatic voltage regulator 3-2 to start up the second generator 2-2 to the third control mode M3 (see Figure 15) in which the start-up time of the second generator 2-2 is relatively short.

[0103] 19, the automatic voltage regulator 3 executes the second control mode M2 ​​(see FIG. 3) as the control mode when the automatic voltage regulator 3 starts up the generator 2, based on the output from the switching unit 6 (more specifically, the switch 6a). Furthermore, the second automatic voltage regulator 3-2 executes the third control mode M3 (see FIG. 15) as the control mode when the second automatic voltage regulator 3-2 starts up the second generator 2-2, based on the output from the switching unit 6 (more specifically, the switch 6a).

[0104] As illustrated in FIG. 20, the power system 111 in FIG. 14 may be replaced with a load circuit 111' that consumes the power received from the generator 2 and / or the second generator 2-2.

[0105] 20, unlike the example shown in Fig. 14, the transformer 4 is not excited by the power grid 111. In the example shown in Fig. 20, it is assumed that the first circuit breaker 51 is in a closed state, the second circuit breaker 56 is in an open state, and the third circuit breaker 56-2 is in an open state. In this case, the control mode is selected depending on which of the second circuit breaker 56 and the third circuit breaker 56-2 is closed first.

[0106] Fig. 20 will be described in more detail. In the example shown in Fig. 20, the power generation system 1C includes: (1) a generator 2 capable of supplying power to a load circuit 111'; (2) a second generator 2-2 capable of supplying power to the load circuit 111'; (3) an automatic voltage regulator 3 that adjusts the output voltage of the generator 2; (4) a second automatic voltage regulator 3-2 that adjusts the output voltage of the second generator 2-2; (5) a transformer 4 arranged between the load circuit 111' and the generator 2 and the second generator 2-2; (6) a first circuit breaker 51 that opens and closes a first current path L1 between the transformer 4 and the load circuit 111'; (7) a second circuit breaker 56 that opens and closes a second current path L2 between the generator 2 and the transformer 4; and (8) a third circuit breaker 56-2 that opens and closes a third current path L3 between the second generator 2-2 and the transformer 4.

[0107] In the example shown in FIG. 20 , the power generation system 1C can execute (9) a fifth connection method in which the second circuit breaker 56 is changed from an open state to a closed state while the third circuit breaker 56-2 remains in an open state, and (10) a sixth connection method in which the third circuit breaker 56-2 is changed from an open state to a closed state after the second circuit breaker 56 is changed to a closed state. Note that, when the fifth connection method is executed, the first circuit breaker 51 may be in a closed state or an open state. In other words, when the fifth connection method is executed, it does not matter which of the first circuit breaker 51 and the second circuit breaker 56 is closed first. Also, when the sixth connection method is executed, the first circuit breaker 51 may be in a closed state or an open state. In other words, when the sixth connection method is executed, it does not matter which of the first circuit breaker 51 and the third circuit breaker 56-2 is closed first.

[0108] Furthermore, in the power generation system 1C, (11) the second automatic voltage regulator 3-2 controls the output voltage of the second generator 2-2 so that the start-up time of the second generator 2-2 when the above-mentioned sixth connection method is executed is shorter than the start-up time of the generator 2 when the above-mentioned fifth connection method is executed. More specifically, when the above-mentioned fifth connection method is executed, the automatic voltage regulator 3-2 executes the second control mode M2 ​​(more specifically, the second control mode M2 ​​in which the start-up time of the generator 2 is relatively long, as exemplified in FIG. 3) as the control mode when starting up the generator 2, whereas when the above-mentioned sixth connection method is executed, the second automatic voltage regulator 3-2 executes the third control mode M3 (more specifically, the third control mode M3 in which the start-up time of the second generator 2-2 is relatively short, as exemplified in FIG. 15) as the control mode when starting up the second generator 2-2.

[0109] In the example shown in FIG. 20, the power generation system 1C can quickly start up the second generator 2-2 while the transformer 4 is excited.

[0110] In the example shown in FIG. 20 , the power generation system 1C can execute (12) a seventh connection method in which the third circuit breaker 56-2 is changed from an open state to a closed state while the second circuit breaker 56 remains in an open state, and (13) an eighth connection method in which the second circuit breaker 56 is changed from an open state to a closed state after the third circuit breaker 56-2 is changed to a closed state. Note that when the seventh connection method is executed, the first circuit breaker 51 may be in a closed state or an open state. In other words, when the seventh connection method is executed, it does not matter which of the first circuit breaker 51 and the third circuit breaker 56-2 is changed to the closed state first. Also, when the eighth connection method is executed, the first circuit breaker 51 may be in a closed state or an open state. In other words, when the eighth connection method is executed, it does not matter which of the first circuit breaker 51 and the second circuit breaker 56 is changed to the closed state first.

[0111] Furthermore, in the power generation system 1C, (14) the automatic voltage regulator 3 controls the output voltage of the generator 2 so that the start-up time of the generator 2 when the above-mentioned eighth connection method is executed is shorter than the start-up time of the second generator 2-2 when the above-mentioned seventh connection method is executed. More specifically, when the above-mentioned seventh connection method is executed, the second automatic voltage regulator 3-2 executes the fourth control mode M4 (more specifically, the fourth control mode M4 in which the start-up time of the second generator 2-2 is relatively long, as exemplified in FIG. 16) as the control mode when starting up the second generator 2-2, whereas when the above-mentioned eighth connection method is executed, the automatic voltage regulator 3 executes the first control mode M1 (more specifically, the first control mode M1 in which the start-up time of the generator 2 is relatively short, as exemplified in FIG. 2) as the control mode when starting up the generator 2.

[0112] In the example shown in FIG. 20, the power generation system 1C can quickly start up the generator 2 while the transformer 4 is excited.

[0113] 20, whether the first circuit breaker 51 is in the open state or the closed state is determined by the switching unit 6 receiving the first state signal S1 from the first circuit breaker 51. Whether the second circuit breaker 56 is in the open state or the closed state is determined by the switching unit 6 receiving the second state signal S2 from the second circuit breaker 56. Whether the third circuit breaker 56-2 is in the open state or the closed state is determined by the switching unit 6 receiving the third state signal S3 from the third circuit breaker 56-2.

[0114] (Fourth embodiment) A power generation system 1D according to the fourth embodiment will be described with reference to Fig. 21 to Fig. 23. Fig. 21 and Fig. 22 are diagrams schematically showing the power generation system 1D according to the fourth embodiment. Fig. 23 is a diagram schematically showing a state in which the fourth soft start time T4 is relatively long when the fourth connection method C4 is executed.

[0115] (Composition / effect) The power generation system 1B in the fourth embodiment includes a current detector 76 and a second current detector 76-2. In the power generation system 1D in the fourth embodiment, when the second connection method C2 is implemented, the rate of increase in the output voltage of the generator 2 is accelerated after the magnetizing inrush current of the transformer 4 has subsided. In addition, in the power generation system 1D in the fourth embodiment, when the fourth connection method C4 is implemented, the rate of increase in the output voltage of the second generator 2-2 is accelerated after the magnetizing inrush current of the transformer 4 has subsided.

[0116] In the fourth embodiment, differences from the first to third embodiments will be mainly described, and a repetitive description of matters already described in the first, second, or third embodiments will be omitted. Therefore, it goes without saying that matters already described in the first, second, or third embodiments can be adopted in the fourth embodiment, even if they are not explicitly described in the fourth embodiment.

[0117] 21, a power generation system 1D in the fourth embodiment includes a generator 2, a second generator 2-2, an automatic voltage regulator 3, a second automatic voltage regulator 3-2, a transformer 4, a first circuit breaker 51, a second circuit breaker 56, a third circuit breaker 56-2, a current detector 76, and a second current detector 76-2. Additionally, the power generation system 1D may include a switching unit 6 (more specifically, a switch 6a), an exciter 11, and a second exciter 11-2. The generator 2, the second generator 2-2, the automatic voltage regulator 3, the second automatic voltage regulator 3-2, the transformer 4, the first circuit breaker 51, the second circuit breaker 56, the third circuit breaker 56-2, the current detector 76, the switching unit 6 (more specifically, the switching unit 6a), the exciter 11, and the second exciter 11-2 have already been described in the first, second, or third embodiment, so repeated description of these components will be omitted.

[0118] 22, the second current detector 76-2 detects the output current of the second generator 2-2. More specifically, the second current detector 76-2 detects the current flowing through the third current path L3 between the second generator 2-2 and the transformer 4.

[0119] As illustrated in FIG. 22, when the fourth connection method C4 is executed (in other words, when the transformer 4 is connected from the second generator 2-2 side and excited), the second automatic voltage regulator 3-2 accelerates the rate of increase of the output voltage of the second generator 2-2 after the magnetizing inrush current of the transformer 4 subsides (see FIG. 23). More specifically, when the output current of the second generator 2-2 detected by the second current detector 76-2 increases beyond a preset second threshold value TH2 and then becomes equal to or less than the second threshold value TH2, it is determined that the magnetizing inrush current has subsided. Furthermore, when it is determined that the magnetizing inrush current of the transformer 4 has subsided, the second automatic voltage regulator 3-2 accelerates the rate of increase of the output voltage of the second generator 2-2.

[0120] (effect) The fourth embodiment has the same effects as the second embodiment. Furthermore, in the fourth embodiment, when the transformer 4 is connected from the second generator 2-2 side and excited, the increase rate of the output voltage of the second generator 2-2 is accelerated after the excitation inrush current of the transformer 4 subsides (see FIG. 23). Therefore, when the transformer 4 is connected from the second generator 2-2 side and excited (see FIG. 22), the start-up time of the second generator 2-2 can be shortened.

[0121] The power system 111 in FIG. 22 may be replaced with a load circuit 111' that consumes the power received from the generator 2 and / or the second generator 2-2.

[0122] The present invention is not limited to the above-described embodiments or modifications, and it is clear that each embodiment or modification can be appropriately modified or changed within the scope of the technical concept of the present invention. Furthermore, various techniques used in each embodiment or modification can be applied to other embodiments or modifications as long as no technical contradiction occurs. Furthermore, optional additional configurations in each embodiment or modification can be omitted as appropriate. [Explanation of symbols]

[0123] 1, 1A, 1B, 1C, 1D...power generation system, 2...generator, 2-2...second generator, 3...automatic voltage regulator, 3-2...second automatic voltage regulator, 4...transformer, 6...switching unit, 6a...switching unit, 11...exciter, 11-2...second exciter, 13...DC power supply, 22...field winding, 31...command value output unit, 33...first calculation unit, 35...pulse signal generator, 36...chopper device, 51...first circuit breaker, 56...second circuit breaker, 56-2...third circuit breaker, 71...voltage detector, 76...current detector, 76-2...second current detector, 79...control device, 101...prime mover, 101-2...second prime mover, 111...power system, 111'...load circuit, C1...first connection method, C2...second connection method, C3...third connection method Formula, C4...Fourth connection method, E1...First switching signal, E2...Second switching signal, F1...First ramp line, F2...Second ramp line, L1...First current path, L2...Second current path, L3...Third current path, M1...First control mode, M2...Second control mode, M3...Third control mode, M4...Fourth control mode, S1...First status signal, S2...Second status signal, S3...Third status signal, T1...First soft start time, T2...Second soft start time, T3...Third soft start time, T4...Fourth soft start time, TH1...First threshold, TH2...Second threshold, TM...First timing, V1...Rated voltage, V1-2...Rated voltage, Va...Voltage detection value, Vg...Voltage command value, Vg-2...Voltage command value

Claims

1. a generator capable of supplying power to a power grid; an automatic voltage regulator that adjusts the output voltage of the generator; a transformer disposed between the power grid and the generator; a first circuit breaker that opens and closes a first current path between the transformer and the power grid; a second circuit breaker that opens and closes a second current path between the generator and the transformer; Equipped with a first connection method in which the second circuit breaker is changed from an open state to a closed state after the first circuit breaker is changed to a closed state, and a second connection method in which the first circuit breaker is changed from an open state to a closed state after the second circuit breaker is changed to a closed state; The automatic voltage regulator shortens the start-up time of the generator when the first connection method is executed compared to the start-up time of the generator when the second connection method is executed. Power generation system.

2. a switching unit that receives a first state signal indicating whether the first circuit breaker is in a closed state or an open state and a second state signal indicating whether the second circuit breaker is in a closed state or an open state, and switches a control mode used by the automatic voltage regulator during start-up of the generator between a first control mode in which the start-up time of the generator is relatively short and a second control mode in which the start-up time of the generator is relatively long, in accordance with the first state signal and the second state signal; When the first state signal indicates a closed state and the second state signal indicates an open state, the switching unit switches the control mode to the first control mode, and when the first state signal indicates an open state and the second state signal indicates a closed state, the switching unit switches the control mode to the second control mode. The power generation system according to claim 1 .

3. a switch that receives a first state signal indicating whether the first circuit breaker is in a closed state or an open state and a second state signal indicating whether the second circuit breaker is in a closed state or an open state, and switches a control mode used by the automatic voltage regulator during start-up of the generator between a first control mode in which the start-up time of the generator is relatively short and a second control mode in which the start-up time of the generator is relatively long, in accordance with the first state signal and the second state signal; When the first state signal indicates a closed state and the second state signal indicates an open state, the switch outputs a first switch signal to the automatic voltage regulator; the automatic voltage regulator executes the first control mode when receiving the first switching signal; The automatic voltage regulator executes the second control mode when it receives a second switching signal different from the first switching signal or when it does not receive the first switching signal. The power generation system according to claim 1 .

4. a current detector for detecting an output current of the generator; When the second connection method is performed, the automatic voltage regulator accelerates the rate of increase of the output voltage of the generator after the magnetizing inrush current of the transformer subsides. The power generation system according to any one of claims 1 to 3.

5. When the second connection method is executed, the automatic voltage regulator increases a voltage command value for adjusting the output voltage of the generator along a gradual increase line over time, and when it is determined that the magnetizing inrush current has subsided during execution of the second connection method, the automatic voltage regulator increases a slope of the gradual increase line, which indicates a rate of increase in the voltage command value for adjusting the output voltage of the generator. The power generation system according to claim 4 .

6. a generator capable of supplying power to a power grid; a second generator capable of supplying power to the power grid; an automatic voltage regulator that adjusts the output voltage of the generator; a second automatic voltage regulator that adjusts the output voltage of the second generator; a transformer disposed between the power grid, the generator, and the second generator; a first circuit breaker that opens and closes a first current path between the transformer and the power grid; a second circuit breaker that opens and closes a second current path between the generator and the transformer; a third circuit breaker that opens and closes a third current path between the second generator and the transformer; Equipped with a first connection method in which the second circuit breaker is changed from an open state to a closed state after the first circuit breaker is changed to a closed state, and a second connection method in which the first circuit breaker is changed from an open state to a closed state after the second circuit breaker is changed to a closed state; the automatic voltage regulator shortens the start-up time of the generator when the first connection method is executed compared to the start-up time of the generator when the second connection method is executed; a third connection method in which the third circuit breaker is closed after the first circuit breaker is closed, and a fourth connection method in which the first circuit breaker is closed after the third circuit breaker is closed, The second automatic voltage regulator shortens the start-up time of the second generator when the third connection method is executed compared to the start-up time of the second generator when the fourth connection method is executed. Power generation system.

7. a generator capable of supplying power to a load circuit; a second generator capable of supplying power to the load circuit; an automatic voltage regulator that adjusts the output voltage of the generator; a second automatic voltage regulator that adjusts the output voltage of the second generator; a transformer disposed between the load circuit, the generator, and the second generator; a first circuit breaker that opens and closes a first current path between the transformer and the load circuit; a second circuit breaker that opens and closes a second current path between the generator and the transformer; a third circuit breaker that opens and closes a third current path between the second generator and the transformer; Equipped with a fifth connection method in which the second circuit breaker is changed from an open state to a closed state while the third circuit breaker remains in an open state; a sixth connection method in which the third circuit breaker is changed from an open state to a closed state after the second circuit breaker is changed to a closed state; a seventh connection method in which the second circuit breaker remains in an open state and the third circuit breaker is changed from an open state to a closed state; and an eighth connection method in which the second circuit breaker is changed from an open state to a closed state after the third circuit breaker is closed, the second automatic voltage regulator controls the output voltage of the second generator so that a start-up time of the second generator when the sixth connection method is executed is shorter than a start-up time of the generator when the fifth connection method is executed; The automatic voltage regulator controls the output voltage of the generator so that the start-up time of the generator when the eighth connection method is executed is shorter than the start-up time of the second generator when the seventh connection method is executed. Power generation system.

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