Protection system, photovoltaic system, and protection method
A protection system including: a DC power supply; a power converter that converts DC power of the DC power supply into AC power, a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path; a DC capacitor connected to a circuit located in the power converter; a timer that counts a lapse of a predetermined length of time from turn-on of the circuit breaker; a current detector that detects current flowing in the power converter; and a protection determiner that issues an open operation command to the circuit breaker when the current detector does not detect a decrease in the current after the timer has counted a lapse of the predetermined length of time from turn-on of the circuit breaker.
1. A protection system comprising:
a DC power supply;
a power converter that converts DC power of the DC power supply into AC power;
a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path;
a DC capacitor connected to a circuit located in the power converter;
a timer that counts a lapse of a predetermined length of time from turn-on of the circuit breaker;
a current detector that detects current flowing in the power converter;
a fuse provided between the DC power supply and the circuit breaker; and
a protection determiner that issues an open operation command to the circuit breaker when the current detector does not detect a decrease in the current after the timer has counted a lapse of the predetermined length of time from turn-on of the circuit breaker and when a short-circuit current flowing at the time of element short-circuiting of an inverter circuit included in the power converter is lower than a current that completely blows out the fuse.
2. A photovoltaic system comprising the protection system according to claim 1 , wherein the DC power supply is a solar cell panel.
3. The protection system according to claim 1 , wherein the protection determiner is provided inside the power converter.
4. A protection method for a power generation system comprising:
a DC power supply;
a power converter that converts DC power of the DC power supply into AC power;
a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path;
a DC capacitor connected to a circuit located in the power converter; and
a fuse provided between the DC power supply and the circuit breaker, the method comprising:
a counting step of counting a lapse of a predetermined length of time from turn-on of the circuit breaker;
a current detection step of detecting current flowing in the power converter; and
a protection determination step of issuing an open operation command to the circuit breaker when a decrease in the current is not detected in the current detection step after a lapse of the predetermined length of time from turn-on of the circuit breaker has been counted in the counting step and when a short-circuit current flowing at the time of element short-circuiting of an inverter circuit included in the power converter is lower than a current that completely blows out the fuse.
5. The protection method according to claim 4 , wherein
the DC power supply is a solar cell panel, and
the power generation system is a photovoltaic system.