Alternating current uninterruptible power supply system

An alternating current uninterruptible power supply system supplying electric power from a fuel cell at the time of power failure of a commercial alternating current power source, comprising:

• a switch provided with a first input part, a second input part, and an output part and allowed to perform, in response to an inputted instruction, switching to a first state that the first input part and the output part are connected to each other or to a second state that the second input part and the output part are connected to each other;
• a first power feed line electrically connected to the first input part of the switch and transmitting electric power from the commercial alternating current power source;
• a second power feed line electrically connected to the second input part of the switch and transmitting electric power from the fuel cell;
• the fuel cell electrically connected to the second power feed line and provided with a stack constructed from a plurality of unit battery cells generating electric power by means of a reaction between fuel gas and oxidation gas and with a plurality of control valves allowed to adjust supply of the fuel gas and the oxidation gas to the stack in response to an inputted instruction;
• a battery allowed to be charged and connected to the second power feed line in parallel to the stack;
• a converter connected between the first power feed line and the second power feed line;
• an inverter connected to the second power feed line between the battery and the second input part;
• an electric power detection part outputting a result corresponding to a state of the electric power from the commercial alternating current power source flowing through the first power feed line;
• a control part;
• a cooling fan supplying wind to the stack;
• and
• a first temperature detection part outputting a result corresponding to a temperature of the inside of a housing containing the fuel cell to the control part, and wherein
• the control part performs at least the following controls a) to d) and h) to j):
• a) a control of, on the basis of the result outputted from the electric power detection part, determining whether or not the electric power supply from the commercial alternating current power source has stopped for a first time or longer;
• b) a control of, if it is determined that the electric power supply from the commercial alternating current power source has stopped for the first time or longer, transmitting an instruction of switching a contact from the first state to the second state to the switch;
• c) a control of, after the control b) described above, on the basis of the result outputted from the electric power detection part, determining whether or not the stopping of the electric power supply from the commercial alternating current power source has continued for a second time or longer which is longer than the first time;
• and
• d) a control of, if it is determined that the stopping of the electric power supply from the commercial alternating current power source has continued for the second time or longer, transmitting an instruction of starting power generation of the fuel cell to the fuel cell;
• h) a control of, in the control a) described above, if it is determined that the electric power supply from the commercial alternating current power source has not stopped for the first time or longer, on the basis of the result from the first temperature detection part, determining whether or not the temperature of the inside of the housing is at or above a threshold;
• i) a control of, if it is determined that the temperature of the inside of the housing is at or above the threshold, transmitting an instruction of operating the cooling fan to the cooling fan;
• and
• j) a control of, after the control i) described above, if it is determined that the temperature of the inside of the housing is not at or above the threshold, transmitting an instruction of stopping the cooling fan to the cooling fan.

An alternating current uninterruptible power supply system supplying electric power from a fuel cell at the time of power failure of a commercial alternating current power source, comprising:

• a switch provided with a first input part, a second input part, and an output part and allowed to perform, in response to an inputted instruction, switching to a first state that the first input part and the output part are connected to each other or to a second state that the second input part and the output part are connected to each other;
• a first power feed line electrically connected to the first input part of the switch and transmitting electric power from the commercial alternating current power source;
• a second power feed line electrically connected to the second input part of the switch and transmitting electric power from the fuel cell;
• the fuel cell electrically connected to the second power feed line and provided with a stack constructed from a plurality of unit battery cells generating electric power by means of a reaction between fuel gas and oxidation gas and with a plurality of control valves allowed to adjust supply of the fuel gas and the oxidation gas to the stack in response to an inputted instruction;
• a battery allowed to be charged and connected to the second power feed line in parallel to the stack;
• a converter connected between the first power feed line and the second power feed line;
• an inverter connected to the second power feed line between the battery and the second input part;
• an electric power detection part outputting a result corresponding to a state of the electric power from the commercial alternating current power source flowing through the first power feed line;
• a control part;
• a first heater receiving electric power through the first power feed line so as to warm a supply source of the fuel gas of the fuel cell;
• and
• a second temperature detection part outputting a result corresponding to a temperature of the supply source of the fuel gas to the control part, and wherein
• the control part performs at least the following controls a) to d) and k) to m):
• a) a control of, on the basis of the result outputted from the electric power detection part, determining whether or not the electric power supply from the commercial alternating current power source has stopped for a first time or longer;
• b) a control of, if it is determined that the electric power supply from the commercial alternating current power source has stopped for the first time or longer, transmitting an instruction of switching a contact from the first state to the second state to the switch;
• c) a control of, after the control b) described above, on the basis of the result outputted from the electric power detection part, determining whether or not the stopping of the electric power supply from the commercial alternating current power source has continued for a second time or longer which is longer than the first time;
• and
• d) a control of, if it is determined that the stopping of the electric power supply from the commercial alternating current power source has continued for the second time or longer, transmitting an instruction of starting power generation of the fuel cell to the fuel cell;
• k) a control of, in the control a) described above, if it is determined that the electric power supply from the commercial alternating current power source has not stopped for the first time or longer, on the basis of the result from the second temperature detection part, determining whether or not the temperature of the supply source of the fuel gas of the fuel cell is at or below a threshold;
• l) a control of, if it is determined that the temperature of the supply source of the fuel gas is at or below the threshold, transmitting an instruction of turning ON the first heater to the first heater;
• and
• m) a control of, after the control l) described above, if it is determined that the temperature of the supply source of the fuel gas is not at or below the threshold, transmitting an instruction of turning OFF the first heater to the first heater.