Power supply system, control method, and storage medium

Abstract

Provided are a power supply system, a control method, and a storage medium that miniaturize a BAT VCU. The power supply system includes a fuel cell, a first transformer that performs voltage conversion on an output voltage of the fuel cell, an electrical storage device, a second transformer that is connected in parallel with the first transformer with respect to a load and performs voltage conversion on an output voltage of the electrical storage device, and a control device. The control device, after the fuel cell is started and before power is supplied to the load, controls the fuel cell to generate less power than is consumed by the load, and after the electrical storage device is charged with the power generated by the fuel cell, controls the power supply system to start supplying power to the load.

Description

Technical Field

[0001] This invention relates to power systems, control methods, and storage media. Background Technology

[0002] When a power outage occurs, an emergency power supply is connected to the load. At this time, the power of the emergency power supply is rapidly drawn from the load, so it must be able to output power to cope with the sudden change in load power from 0% to 100%. In recent years, as an emergency power supply, in order to mitigate the adverse effects on the earth's environment, there have been emergency power supplies that use fuel cells (see, for example, Patent Document 1 (Japanese Patent Application Publication No. 2002-118979)).

[0003] Figure 5 This diagram illustrates a structural example where a fuel cell is used as an emergency power source. Figure 5 The diagram shows a power system including a fuel cell (FC), a fuel cell VCU (FC VCU), a battery VCU (BAT VCU), and a battery.

[0004] The FC VCU controls FC power. The BAT VCU controls battery power. Figure 5 As shown, a battery with higher responsiveness than an FC is connected in parallel with an FC.

[0005] Figure 6 It is a graph showing the change in electrical power when a load is connected. For example... Figure 6 As shown, when a load is connected, the output from the battery rises from 0% to 100%. Afterward, the output from the battery takes approximately 2 seconds to decrease back to 0% as the FC output power increases. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Thus, when a load is connected, the battery needs to output 100% of the load power, therefore a large BAT VCU capable of supplying 100% of the load power is required.

[0008] This invention was made with the consideration of such circumstances in mind, and one of its objectives is to provide a technique for miniaturizing BAT VCU.

[0009] Solution for solving the problem

[0010] The power supply system of the present invention adopts the following structure.

[0011] (1): One aspect of the present invention relates to a power supply system, wherein the power supply system comprises: a fuel cell; a first transformer for voltage conversion of the output voltage of the fuel cell; an energy storage device; a second transformer connected in parallel with the first transformer relative to a load and for voltage conversion of the output voltage of the energy storage device; and a control device that, after the fuel cell is started and before power is supplied to the load, controls the fuel cell to generate less power than the power consumed by the load, and after the energy storage device is charged with the power generated by the fuel cell, controls the power supply from the power supply system to the load to begin.

[0012] (2): Based on the power system of the above (1) scheme, the control device may also control the fuel cell to generate approximately half of the power consumed by the load after the fuel cell is started and before power is supplied to the load, and control the power supply from the power system to the load to begin after the fuel cell generates power to the energy storage device.

[0013] (3): One aspect of the present invention relates to a control method in which a power system comprises: a fuel cell; a first transformer that performs voltage transformation on the output voltage of the fuel cell; an energy storage device; and a second transformer that is connected in parallel with the first transformer relative to a load and performs voltage transformation on the output voltage of the energy storage device. The control method causes one or more computers to perform the following processing: after the fuel cell is started and before power is supplied to the load, control to make the fuel cell generate less power than the power consumed by the load, and after charging the energy storage device with the power generated by the fuel cell, control to start supplying power from the power system to the load.

[0014] (5): One aspect of the present invention relates to a storage medium storing a program, wherein a power system comprises: a fuel cell; a first transformer for voltage conversion of the output voltage of the fuel cell; an energy storage device; and a second transformer connected in parallel with the first transformer relative to a load and for voltage conversion of the output voltage of the energy storage device, the program causing one or more computers to perform the following processing: after the fuel cell is started and before power is supplied to the load, controlling the fuel cell to generate less power than the power consumed by the load, and after the energy storage device is charged with the power generated by the fuel cell, controlling the power supply from the power system to the load to begin.

[0015] Invention Effects

[0016] According to the schemes (1) to (5), the output of the energy storage device can be made smaller than before, thus enabling the miniaturization of the BATVCU. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating a structural example, including the power supply system 10 of the implementation method.

[0018] Figure 2 This is a diagram showing an example of the structure of the power supply device 200.

[0019] Figure 3 It is a line graph showing the changes in each parameter.

[0020] Figure 4 This is a flowchart showing the control content of the control device 100.

[0021] Figure 5 This is a diagram illustrating a structural example of a previous technology.

[0022] Figure 6 It is a graph showing the change in power when a load is connected in conventional technology.

[0023] Explanation of reference numerals in the attached figures:

[0024] 10 Power System

[0025] 20 Generator Control Panel

[0026] 52 resistor

[0027] 53 and 54 diodes

[0028] 55 reactor

[0029] 56 capacitor

[0030] 100 control device

[0031] 200 power supply unit

[0032] 210, 210-1, 210-2FCS

[0033] 212-1FC VCU

[0034] 220BAT VCU

[0035] 230 battery

[0036] 250 Current Sensor

[0037] 300 Automatic Control Panel

[0038] 400 inverter

[0039] 500 circuit breaker

[0040] 600 various relays

[0041] 800 switching unit

[0042] 900UPS

[0043] 1000 load. Detailed Implementation

[0044] Hereinafter, embodiments of the power supply system, control method, and storage medium of the present invention will be described with reference to the accompanying drawings.

[0045] Figure 1 This is a diagram illustrating a structural example, including the power supply system 10 according to an embodiment of the present invention. Figure 1 The diagram shows a power system 10, an inverter 400, a generator control panel 20, a power grid 700, a switching unit 800, a UPS (Uninterruptible Power Supply) 900, and a load 1000. Figure 1 In this diagram, solid lines represent power lines, and dashed lines represent communication lines. A good example of a communication protocol that uses communication lines is CAN (Controller Area Network).

[0046] Power system 10 supplies power to the load when the power supply from the transmission network 700 is interrupted. Inverter 400 converts the DC power output from power system 10 into AC power. Generator control panel 20 includes circuit breaker 500 and various relays 600. Circuit breaker 500, under the control of automatic control panel 300, uses switching unit 800 to switch the power supply source to the load to either the transmission network 700 or power system 10. The various relays 600 are, for example, frequency relays, overcurrent relays, overvoltage / undervoltage relays, and current-to-ground detection relays.

[0047] The automatic control panel 300 controls the power supply system 10, the inverter 400, and the generator control panel 20. The power grid 700 is the power system of the power company, etc., that supplies power to the load 1000. The UPS temporarily supplies power to the load 1000 when the power supply to the load 1000 is interrupted.

[0048] The power system 10 includes a control device 100 and a power supply device 200. The control device 100 controls the power supply device 200. The power supply device 200 uses a fuel cell to supply electricity. It should be noted that the power system 10 is equipped with various auxiliary machines involved in the power supply device 200, batteries for operating the auxiliary machines, and a hydrogen supply mechanism that supplies hydrogen to the power supply device 200 under the control of an automatic control panel 300, but these are omitted.

[0049] Figure 2 This diagram illustrates a structural example of a power supply unit 200. The power supply unit 200 includes two FCS (Fuel Cell Stacks) 210-1 and 210-2, a BAT VCU (Battery Voltage and Current Control Unit) 220, a battery 230, and a current sensor 250. Without specifically distinguishing between FCS 210-1 and 210-2, it is represented as FCS 210. A structure of two FCS 210s is shown as an example, but one or more are acceptable. Commands from the control device 100 can be transmitted to the FC 210. The battery 230 is an example of an energy storage device.

[0050] FCS210-1 and 210-2 are connected in parallel with the load. BAT VCU220 is connected in series with battery 230, and BAT VCU220 and battery 230 are connected in parallel with FCS. The inverter 400 outputs load current I and DC bus voltage V. The control device 100 calculates the load power P based on the load current I and DC bus voltage V detected by current sensor 250, and issues a current command set to current I1 so that FCS210 can output power P / 2 respectively. It should be noted that when N FCSs are connected in parallel, the control device 100 issues a current command set to current I1 so that FCS210 can output power P / N respectively.

[0051] Since both FCS210 units have the same structure, FCS210-1 will be used to describe the structure. FCS210-1 consists of FC (Fuel Cell) 211-1 and FC VCU (Fuel Cell Voltage and Current Control Unit) 212-1. Resistor 52 and diode 53 are directly connected to the positive side of FC211-1. The cathode of diode 53 is connected to terminal A. The anode of diode 53 is connected to resistor 52. Reactor 55 and diode 54 are connected in parallel, and reactor 55 and diode 54 are connected to terminals C and D, respectively. Terminal C is located between resistor 52 and diode 53. Terminal D is connected to the negative side of FC211-1. Capacitor 56 is connected to terminals E and F. Terminal E is connected to the cathode side of diode 53. Terminal F is connected to the negative side of FC211-1. In the following description, unless otherwise specified, FC211-1 and 211-2 are referred to as FC211. Unless otherwise specified, FC VCU212-1 and 212-2 are referred to as FC VCU212. FCVCU212 is an example of a first transformer that transforms the output voltage of a fuel cell.

[0052] Battery 230 supplies power when the load is connected. Battery 230 is a more responsive battery compared to FC211-1 and 211-2. BAT VCU220 is connected in parallel with FC VCU212 relative to load 1000, and performs voltage transformation on the output voltage of battery 230, as well as power regeneration for stabilizing the DC bus voltage supply and suppressing FC OCV (Open Circuit Voltage). BAT VCU220 is an example of a second transformer.

[0053] Based on the above structure, the control content of this embodiment will be explained. Figure 3 This is a line graph showing the changes in various parameters under control based on this embodiment. Figure 3 The graph shows the load power, FC output power, battery output power, and FC voltage. The upper part of the time axis represents the changes in load power, FC output power, and battery output power; the unit of this vertical axis is power. The lower part of the time axis represents the changes in FC voltage; the unit of this vertical axis is voltage. Figure 3 In the diagram, load power and FC voltage are represented by solid lines. FC output power is represented by a single-dot dashed line. Battery output power is represented by a two-dot dashed line.

[0054] Here, the above-mentioned load power refers to the power supplied to the load. FC output power refers to the power output by FC211. Battery output power refers to the power output by battery 230. FC voltage refers to the voltage output by FC211. Figure 3 The terms "100%" and "50%" indicate the proportion relative to the power preset for use by the load. When the power preset for use by the load is set to X, 100% is X and 50% is 0.5X. In the following explanation, the power preset for use by the load may sometimes be expressed as the power used by the load.

[0055] exist Figure 3 The diagram shows the timings Ta, Tb, Tc, and Td. Timing Ta represents the moment when power to the transmission network 700 is cut off, indicating the moment when hydrogen is supplied to FC211. Timing Tb represents the moment when the suppression control of FC OCV begins. Timing Tc represents the moment when FC startup preparation is complete. Timing Td represents the moment when power system 10 is connected to load 1000.

[0056] First, at timing Ta, when hydrogen is supplied to FC211, FC211 begins generating electricity. As a result, the FC voltage gradually increases. When the FC voltage reaches the OCV suppression voltage (timing Tb), BAT VCU220 initiates FC OCV suppression control, thereby gradually reducing the FC voltage. With the initiation of FC OCV suppression control, current begins to flow, thus increasing the FC output power. Meanwhile, the battery 230 is charged by an amount corresponding to the FC output power. It should be noted that by reducing the OCV suppression voltage, the start-up preparation time can be shortened.

[0057] When the FC output power reaches 50% of the load's utilization power and the FC startup preparation is complete (timing Tc), the power system 10 is connected to the load 1000 via the switching unit 800 at timing Td. At this time, the FC output power has reached 50% of the load's utilization power, so the battery output power of 50% of the load's utilization power is sufficient. That is, since it can be half the power as before, the BAT VCU can be miniaturized. After timing Td, the FC output power increases, and simultaneously, the battery output power decreases to zero.

[0058] Here, we will explain the case where the FC output power is 50% of the load utilization power. If the FC output power is A% greater than 50% of the load utilization power, for example, at time Tc, the battery 230 is subjected to a charging load greater than 50% by A%, which is undesirable. On the other hand, if the FC output power is B% less than 50% of the load utilization power, for example, at time Tc, the battery 230 must output B% more than 50%. Therefore, compared to the case where a 50% output from the battery is sufficient, the BAT VCU cannot be miniaturized. Based on the above, theoretically, it is optimal to make the FC output power 50% of the load utilization power. It should be noted that the main point of this embodiment is to make the FC output power greater than 0% before connecting to the load, thereby enabling miniaturization of the BAT VCU. Therefore, the FC output power before connecting to the load can be appropriately set according to the circuit structure, operating environment, etc.

[0059] The controls described above are illustrated using a flowchart. Figure 4 This is a flowchart illustrating the control content of the control device 100. The flowchart shows the processing starting from time Ta. Figure 4 The flowchart shown illustrates the processing flow in a structure with N FCS210s.

[0060] exist Figure 4In step S101, the control device 100 determines whether the FC voltages of all N FCS210s have reached or exceeded the OCV suppression voltage. Here, the control device 100 is periodically notified of the FC voltages from the N FCS210s, and the control device 100 uses the FC voltages to perform the determination in step S101.

[0061] When the FC voltage of all N FCS210s becomes above the OCV suppression voltage in step S101, the control device 100 instructs the BAT VCU220 to start OCV suppression voltage control (step S102). OCV suppression voltage control refers to control that prevents the voltage from exceeding the OCV suppression voltage. The control device 100 determines whether the output power of all FCS210s has reached 50% of the load utilization power (step S103). If the output power of all FCS210s reaches 50% of the load utilization power in step S103, the control device 100 requests the automatic control panel 300 to switch the switching unit 800, thereby connecting the power system 10 to the load 1000 (step S104). After that, the process of this flowchart ends. It should be noted that the automatic control panel 300, which requests the switching unit 800 to switch, requests the circuit breaker 500 to switch the connection to the destination by the switching unit 800.

[0062] As explained above, after FC211 is started and before power is supplied to load 1000, control device 100 controls FC211 to generate less power than that consumed by load 1000 (e.g., approximately half (50%) of the power), and after the power generated by FC211 is charged into battery 230, control device 100 controls to start supplying power from power system 10 to load 1000.

[0063] According to this embodiment, the output of the energy storage device can be reduced compared to the past, thus enabling the miniaturization of the BAT VCU.

[0064] The implementation methods described above can be performed as follows.

[0065] A power supply system comprising: a fuel cell; a first transformer for voltage conversion of the output voltage of the fuel cell; an energy storage device; and a second transformer connected in parallel with the first transformer relative to a load, and for voltage conversion of the output voltage of the energy storage device, the power supply system comprising:

[0066] Storage medium, which stores computer-readable instructions; and

[0067] The processor, which is connected to the storage medium,

[0068] The processor performs the following processing by executing computer-readable instructions:

[0069] After the fuel cell starts up and before power is supplied to the load, the control is set to make the fuel cell generate less power than the power consumed by the load, and after the power generated by the fuel cell is charged into the energy storage device, the control is set to start supplying power from the power system to the load.

[0070] The above description illustrates specific embodiments of the present invention, but the present invention is not limited to such embodiments in any way, and various modifications and substitutions can be made without departing from the spirit of the present invention.

Claims

1. A power supply system, wherein, The power supply system includes: Fuel cells; The first transformer performs voltage transformation on the output voltage of the fuel cell; Energy storage devices; The second transformer is connected in parallel with the first transformer relative to the load and performs voltage transformation on the output voltage of the energy storage device; as well as Control device, After the fuel cell starts up and before power is supplied to the load, the control device controls the fuel cell to generate less power than the power consumed by the load, and after the power generated by the fuel cell is charged into the energy storage device, it controls the power supply from the power system to the load to begin.

2. The power supply system according to claim 1, wherein, After the fuel cell starts up and before power is supplied to the load, the control device controls the fuel cell to generate approximately half of the power consumed by the load, and after the power generated by the fuel cell is charged into the energy storage device, it controls the power supply from the power system to the load to begin.

3. A control method, wherein, The power system includes: Fuel cells; The first transformer performs voltage transformation on the output voltage of the fuel cell; Energy storage devices; as well as The second transformer is connected in parallel with the first transformer relative to the load, and performs voltage transformation on the output voltage of the energy storage device. In the power supply system, the control method causes one or more computers to perform the following processing: After the fuel cell starts up and before power is supplied to the load, the control is set to make the fuel cell generate less power than the power consumed by the load, and after the power generated by the fuel cell is charged into the energy storage device, the control is set to start supplying power from the power system to the load.

4. A storage medium storing a program, wherein, The power system includes: Fuel cells; The first transformer performs voltage transformation on the output voltage of the fuel cell; Energy storage devices; as well as The second transformer is connected in parallel with the first transformer relative to the load, and performs voltage transformation on the output voltage of the energy storage device. In the power supply system, the program causes one or more computers to perform the following processing: After the fuel cell starts up and before power is supplied to the load, the control is set to make the fuel cell generate less power than the power consumed by the load, and after the power generated by the fuel cell is charged into the energy storage device, the control is set to start supplying power from the power system to the load.

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