JP-7857242-B2 - Grid-connected fuel cell system and power receiving control method

JP7857242B2JP 7857242 B2JP7857242 B2JP 7857242B2JP-7857242-B2

Inventors

大島昭一

Assignees

株式会社東芝
東芝エネルギーシステムズ株式会社

Dates

Publication Date: 20260512
Application Date: 20230310

Claims (15)

Multiple fuel cell systems that reduce output power based on the value of power received from the power grid, The system includes a comparator that is hardwired with metal wires to the plurality of fuel cell systems, compares the value of the power received from the power grid with a set value, and outputs a power drop signal to the plurality of fuel cell systems without signal conversion based on the result of the comparison. The plurality of fuel cell systems are interconnected fuel cell systems that reduce the output power based on the value of the power drop signal.
The fuel cell system according to claim 1, wherein the fuel cell system receives the input of the power drop signal via the metal wire .
The fuel cell system is a grid-connected fuel cell system according to claim 1, wherein the fuel cell system reduces the output power by a predetermined reduction amount per unit time.
The interconnected fuel cell system according to claim 1, wherein the comparator outputs the power drop signal based on the value of the received power in the analog signal.
Multiple fuel cell systems that reduce output power based on the value of power received from the power grid, A first comparator is hardwired with the plurality of fuel cell systems by metal wires , compares the power received from the power grid with a first set value, and outputs a first power drop signal to the plurality of fuel cell systems without signal conversion based on the result of the comparison . The system comprises a plurality of fuel cell systems and a second comparator that is hardwired with the metal wire , compares the power received from the power grid with a second set value, and outputs a second power drop signal to the plurality of fuel cell systems without signal conversion based on the result of the comparison , The plurality of fuel cell systems reduce the output power based on the value of the first power drop signal and the value of the second power drop signal. Grid-connected fuel cell system.
The interconnected fuel cell system according to claim 5, wherein the fuel cell system receives input of the first and second power drop signals via the metal wire .
The aforementioned fuel cell system Based on the value of the first power drop signal, the output power is reduced by a predetermined reduction amount determined by the first control value at each unit time. Based on the value of the second power drop signal, the output power is reduced by a predetermined reduction amount determined by a second control value different from the first control value, at each unit time. The interconnected fuel cell system according to claim 5.
The aforementioned fuel cell system Based on the value of the first power drop signal, the output power is reduced by a predetermined reduction amount determined by the first control value at each unit time. Based on the value of the second power drop signal, the output power is reduced until the output power stops. The interconnected fuel cell system according to claim 5.
The interconnected fuel cell system according to claim 5, wherein the first and second comparators output the first and second power drop signals based on the value of the received power in the analog signal.
The system further comprises a third comparator that is hardwired with the plurality of fuel cell systems by metal wires, compares the power received from the power grid with a third set value, and outputs a third power drop signal to the plurality of fuel cell systems without signal conversion based on the result of the comparison . The plurality of fuel cell systems reduce the output power based on the value of the first power drop signal, the value of the second power drop signal, and the value of the third power drop signal. The interconnected fuel cell system according to claim 5.
The interconnected fuel cell system according to claim 10, wherein the fuel cell system reduces the output power until the output power stops, based on the value of the third power drop signal.
Multiple fuel cell systems reduce their output power based on the power received from the power grid. A comparator, hardwired with the aforementioned fuel cell systems by metal wires , compares the power received from the power grid with a set value based on the comparison result, and outputs a power drop signal to the aforementioned fuel cell systems without signal conversion . The plurality of fuel cell systems reduce the output power based on the value of the power drop signal. A method for controlling received power, including the following.
The power receiving control method according to claim 12, wherein the fuel cell system receives the power drop signal input via the metal wire .
The power receiving method according to claim 12, wherein the fuel cell system reduces the output power by a predetermined reduction amount per unit time.
The power receiving control method according to claim 12, wherein the comparator outputs the power drop signal based on the value of the received power in the analog signal.

Description

Embodiments of the present invention relate to a grid-connected fuel cell system and a method for controlling received power. There is a technology that distinguishes between reverse power flow during standalone operation of distributed power sources such as fuel cell systems and temporary reverse power flow other than that during standalone operation, thereby ensuring the continuous and stable operation of distributed power sources in the power grid. Reverse power flow refers to the flow of electricity generated on the consumer side back into the power grid. For example, if the electricity generated on the consumer side is greater than the electricity consumed on the consumer side, the surplus electricity flows back into the power grid. Temporary reverse power flow occurs, for example, due to sudden load fluctuations occurring within the consumer's premises. Furthermore, in self-consumption power generation, conventional fuel cell systems adjust the transmitted power to maintain it within a certain range in order to prevent reverse power flow. For example, conventional fuel cell systems calculate the power value at the receiving point at the connection point with the power grid and the power value at the transmitting end of the fuel cell system using a control circuit, and adjust the transmitted power in response to changes in load. Japanese Patent Publication No. 2017-121149 This is an overall configuration diagram of the interconnected fuel cell system in the first embodiment.This is an overall configuration diagram of a grid-connected fuel cell system of a comparative example of the first embodiment.This is an example of a flowchart illustrating the operation of the comparator in the first embodiment.This is an example of a flowchart of the logic circuit of the fuel cell system in the first embodiment.This is an example of reverse power flow prevention control in the first embodiment.This is an overall configuration diagram of the interconnected fuel cell system in the second embodiment.This is an example of a flowchart of the logic circuit of the fuel cell system in the second embodiment. The embodiments of this disclosure will be described below with reference to the drawings. These embodiments are not limiting to the present invention. The drawings are schematic or conceptual, and the proportions of each part may not necessarily be identical to those of actual objects. In the specification and drawings, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals, and detailed descriptions are omitted where appropriate. (First Embodiment) Figure 1 is an overall diagram of the interconnected fuel cell system in the first embodiment. The grid-connected fuel cell system 1 is installed, for example, in a plant such as a factory. The grid-connected fuel cell system 1 supplies the generated electricity to loads 4 within the factory, thereby covering the factory's power consumption. Furthermore, the grid-connected fuel cell system 1 may be used in combination with a PV (photovoltaic) power generation device 5. By supplying the electricity generated by the grid-connected fuel cell system 1 and the PV 5 to loads 4, the factory's power consumption is covered. In this example, PV5 was chosen as the renewable energy power generation system to be combined with the grid-connected fuel cell system 1, but other power generation methods may also be used. For example, the grid-connected fuel cell system 1 may be used in combination with other renewable energy power generation devices such as wind power generators or biomass power generators. Furthermore, the grid-connected fuel cell system 1 may be used in combination with an emergency generator. The same applies to the following examples. Furthermore, for the sake of simplicity, the following explanation assumes that PV5 does not supply power to load 4. Also, for the sake of explanation, in the overall configuration diagram, power supply lines are represented by solid lines, and communication lines by dashed lines. In operation, the interconnected fuel cell system 1 does not rely solely on the output power of the fuel cell system 9 to meet all load capacities. Instead, it supplements its power supply with power from the power grid 3, providing a margin against reverse power flow. For example, if the maximum output power of the interconnected fuel cell system 1 is 1 MW and the total load of load 4 is 1 MW, it is conceivable to supply 800 kW of power from the interconnected fuel cell system 1 to load 4 and 200 kW of power from the power grid 3 to load 4. This ensures that even if the load capacity of load 4 decreases slightly, any unused power will not flow back into the power grid 3. The interconnected fuel cell system 1 needs to implement reverse power flow prevention control to ensure that the value of this received power does not become negative. Another method to prevent reverse power flow is to con