Power source system and its operation method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is a power supply system that combines a pressurized solid oxide fuel cell (sometimes referred to simply as "SOFC" herein) and power generation by a micro gas turbine (simply a "hybrid system" herein). ) And its operation method.

【0002】

[Conventional technology]

A hybrid power generation system combining SOFC and a micro gas turbine is conventionally known. Figure 2 shows the power generation efficiency with respect to the output when the SOFC is operated independently. As can be seen from Fig. 2, the point where the power generation efficiency is maximized remains low with respect to the rated output (100% output).

【0003】

On the other hand, Fig. 3 shows the power generation efficiency with respect to the output in the hybrid power generation system that combines SOFC and micro gas turbine. As can be seen from FIG. 3, in such a hybrid power generation system, the point where the power generation efficiency is highest is when the output is slightly lower than the rated output. Therefore, high efficiency can be obtained even when operating at a large output close to the rated output.

【0004】

[Problems to be Solved by the Invention]

In the hybrid power generation system as described above, it is preferable from the viewpoint of power generation efficiency to always operate at a large output close to the rated output as described above. However, as is well known, there is a large difference in power demand between daytime and nighttime, and the amount of power required decreases at nighttime. In order to deal with this, it is necessary to reduce the amount of power generation, and there is a problem that the power generation efficiency is lowered. In addition, the equipment must have a capacity sufficient to meet the daytime power demand, and there is also a problem that equipment larger than the average power demand is required.

【0005】

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power supply system and an operation method thereof so that the above-mentioned hybrid power generation system can always be operated with high efficiency.

【0006】

[Means for solving problems]

The first means for solving the above-mentioned problems includes a pressurized solid oxide fuel cell (SOFC), a micro gas turbine to which a generator is connected, and a redox flow battery. The sum of the output from the generator is output to the power system as basic power, and when the amount of power required by the power system is larger than the basic power, the redox flow battery uses the power corresponding to the difference between the two to the power system. The power supply system (claim 1) is characterized in that it has a function of storing the electric energy corresponding to the difference between the two when the electric energy to be supplied and required by the electric power system is smaller than the basic electric energy.

【0007】

According to this means, the value of the basic power is always kept in a highly efficient region near the rated value, and at night when the required power is less than the basic power, the redox flow battery is charged with the surplus power to charge the required power. If the power exceeds the basic power, the shortage can be supplied from the redox flow battery. Therefore, the power generation efficiency of the hybrid power generation system can be kept high, and the scale of the entire equipment can be made commensurate with the average demand power.

【0008】

The second means for solving the above-mentioned problems is a method of operating the first means, in which the total power generation efficiency of the basic power generated by the SOFC and the power generated by the micro gas turbine is almost the highest. It is characterized in that the operation is performed while maintaining the power amount (claim 2).

【0009】

In this means, even if the required power amount exceeds the rated output, the output of the hybrid system is not raised to the rated value, and the power generation efficiency is almost the highest (power generation of 97% or more of the maximum power generation efficiency). Continue operation while maintaining the efficiency range), and supply the insufficient power from the redox flow battery. Therefore, the power generation efficiency of the hybrid system can be reliably maintained at high efficiency.

【0010】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a power supply system which is an example of the embodiment of the present invention. Combustion air to the SOFC is supplied to the compressor directly connected to the micro gas turbine, and the compressed air is heated by the heat exchanger and then sent to the SOFC, where it is mixed with the fuel also heated through the heat exchanger. To generate power. The DC output of the SOFC is converted into a high-voltage DC voltage by the D / D converter and input to the DC line.

【0011】

The SOFC exhaust gas at about 850 ° C is sent to the micro gas turbine to drive the micro gas turbine. A generator G is coupled to the micro gas turbine, and the AC power generated by this is converted to DC by the A / D converter and input to the DC line. Then, the exhaust gas of about 250 ° C. discharged from the micro gas turbine is radiated by the heat exchanger, and then the heat medium is heated by the heat recovery / cold / hot heat supply device and then exhausted.

【0012】

The total of the amount of power generated by the SOFC and the amount of power generated by the generator G is controlled by the command of the optimized operation system to the amount of power generated at which the power generation efficiency of the hybrid system composed of these is maximized. That is, the total of the amount of power generated by the SOFC and the amount of power generated by the generator G is always kept constant (this is called "basic power").

【0013】

A vanadium redox flow battery is coupled to the DC line. The vanadium redox flow battery receives a command from the optimized operation system, and when the amount of power required by the power system exceeds the basic power, it performs power supply control and discharges the insufficient power to the DC line. Further, when the basic electric power exceeds the amount of electric power required by the electric power system, power supply control is performed to receive the surplus electric power from the DC line and store the electric power.

【0014】

The bidirectional inverter converts the power of the DC line into alternating current synchronized with the power system and supplies it to the power system. The heat medium supplied from the heat recovery / cold / hot heat supply device heats the electrolytic solution in the electrolytic solution tank of the vanadium redox flow battery and is supplied to the outside as a heat source.

【0015】

The optimized operation system controls for a high degree of optimum operation not described in the present specification, but at a minimum, it controls the discharge and storage of the vanadium redox flow battery as described above.

【0016】

[Effect of the invention]

As described above, according to the present invention, it is possible to provide a power supply system and an operation method thereof so that the above-mentioned hybrid power generation system can always be operated with high efficiency. Further, the equipment can be downsized as compared with the conventional case.

[Simple explanation of drawings]

[Figure 1]

It is a schematic diagram of the power supply system which is one example of the Embodiment of this invention.

[Figure 2]

It is a figure which shows the power generation efficiency with respect to the output when SOFC is operated independently.

[Fig. 3]

It is a figure which shows the power generation efficiency with respect to the output in the hybrid power generation system which combined the micro gas turbine and SOFC.