Energy coupling method and system for household energy storage

1 . An energy coupling method for household energy storage, performed by an energy management system (EMS), the method comprising:

monitoring an electricity grid supplying power to a household electricity grid that is managed by the EMS;

in response to an outage of the electricity grid, disconnecting the household electricity grid from the electricity grid, and controlling a battery energy storage system (BESS) to supply a backup alternating current (AC) power to a household load connected to the household electricity grid;

monitoring a power consumption rate of the household load;

in response to the power consumption rate of the household load exceeding a pre-determined power consumption rate threshold, turning on a portable generator that is connected to the household electricity grid through an AC-to-AC converter, the AC-to-AC converter being capable of outputting a generated AC power that is synchronized to the household electricity grid;

in response to an input AC voltage inputted into the AC-to-AC converter from the portable generator being smaller than a voltage value, comparing a frequency of the input AC voltage inputted into the AC-to-AC converter from the portable generator with a frequency value; and

in response to the frequency of the input AC voltage inputted into the AC-to-AC converter from the portable generator being greater than or equal to the frequency value, maintaining an actual output power outputted from the AC-to-AC converter.

2 . The energy coupling method according to claim 1 , further comprising:

monitoring an energy capacity of a battery of the BESS; and

in response to the energy capacity of the battery of the BESS dropping below a first energy capacity value, controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid.

3 . The energy coupling method according to claim 2 , wherein:

the generated AC power outputted from the AC-to-AC converter supplies to the household load, charges the battery of the BESS, or supplies to the household and charges the battery of the BESS.

4 . The energy coupling method according to claim 3 , further comprising:

after controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid in response to the energy capacity of the battery of the BESS dropping below the first energy capacity value, continuing to monitor the energy capacity of the battery of the BESS; and

in response to the energy capacity of the battery of the BESS exceeding a second energy capacity value, controlling the AC-to-AC converter to stop supplying the generated AC power to the household electricity grid, the second energy capacity value being greater than the first energy capacity value.

5 . The energy coupling method according to claim 4 , wherein controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid includes:

obtaining a target output power for the generated AC power outputted from the AC-to-AC converter;

determining whether the actual output power outputted from the AC-to-AC converter is greater or smaller than the target output power;

in response to the actual output power being greater than the target output power, controlling the AC-to-AC converter to reduce the actual output power to being equal to the target output power; and

in response to the actual output power being smaller than the target output power, controlling the AC-to-AC converter to repeatedly increase the actual output power by an incremental power step until a difference between the target output power and the actual output power is smaller than the incremental power step.

6 . The energy coupling method according to claim 5 , further comprising:

in response to the input AC voltage inputted into the AC-to-AC converter from the portable generator being greater than the voltage value, controlling the AC-to-AC converter to maintain the actual output power.

7 . The energy coupling method according to claim 1 , after turning on the portable generator, further comprising:

monitoring the input AC voltage inputted into the AC-to-AC converter from the portable generator; and

in response to the input AC voltage inputted into the AC-to-AC converter from the portable generator dropping below a voltage value, controlling the AC-to-AC converter to stop supplying the generated AC power to the household electricity grid.

8 . The energy coupling method according to claim 1 , after turning on the portable generator, further comprising:

controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid.

9 . The energy coupling method according to claim 1 , further comprising:

in response to a recovery of the electricity grid, re-connecting the household electricity grid to the electricity grid, and turning off the portable generator.

10 . The energy coupling method according to claim 9 , further comprising:

in response to the recovery of the electricity grid, controlling the BESS to stop supplying the backup AC power to the household load connected to the household electricity grid and to charge a battery of the BESS.

11 . The energy coupling method according to claim 1 , wherein:

the AC-to-AC converter includes an input terminal for receiving an output AC power from the portable generator, an output terminal for connecting to the household electricity grid, a power converter circuit for converting the output AC power from the portable generator into the generated AC power that is synchronized to the household electricity grid, and a communication interface for communicating with the EMS.

12 . The energy coupling method according to claim 11 , wherein:

the EMS communicates with the AC-to-AC converter through at least one of an Ethernet connection, a controller area network (CAN) bus, an RS-485 serial control bus, a Wi-Fi connection, or a Bluetooth connection; and

the EMS communicates with a smart phone application through at least one of the Ethernet connection, the Wi-Fi connection, or a mobile network connection, the smart phone application allowing a user to manage the household electricity grid.

13 . The energy coupling method according to claim 12 , wherein:

at least one of the EMS or the smart phone application controls the AC-to-AC converter to perform one or more operations including:

turning on the AC-to-AC converter;

turning off the AC-to-AC converter;

controlling an output power;

retrieving the output power;

retrieving an amplitude and a frequency of an input AC voltage from the portable generator;

retrieving an amplitude and a frequency of the generated AC power;

retrieving a current value of the input AC voltage from the portable generator;

retrieving a current value of the generated AC power; and

retrieving alarms of the AC-to-AC converter.

14 . An energy coupling system for household energy storage, comprising an energy management system (EMS), wherein the EMS includes one or more processors and one or more memories storing program instructions that when executed by the one or more processors, cause the one or more processors to:

monitor an electricity grid supplying power to a household electricity grid that is managed by the EMS;

in response to an outage of the electricity grid, disconnect the household electricity grid from the electricity grid, and control a battery energy storage system (BESS) to supply a backup alternating current (AC) power to a household load connected to the household electricity grid;

monitor a power consumption rate of the household load; and

in response to the power consumption rate of the household load exceeding a pre-determined power consumption rate threshold, turn on a portable generator that is connected to the household electricity grid through an AC-to-AC converter, the AC-to-AC converter being capable of outputting a generated AC power that is synchronized to the household electricity grid;

in response to an input AC voltage inputted into the AC-to-AC converter from the portable generator being smaller than a voltage value, compare a frequency of the input AC voltage inputted into the AC-to-AC converter from the portable generator with a frequency value; and

in response to the frequency of the input AC voltage inputted into the AC-to-AC converter from the portable generator being greater than or equal to the frequency value, maintain an actual output power outputted from the AC-to-AC converter.

15 . The energy coupling system according to claim 14 , wherein the one or more processors are further configured to:

monitor an energy capacity of a battery of the BESS; and

in response to the energy capacity of the battery of the BESS dropping below a first energy capacity value, control the AC-to-AC converter to supply the generated AC power to the household electricity grid.

16 . The energy coupling system according to claim 15 , wherein:

the generated AC power outputted from the AC-to-AC converter supplies to the household load, charges the battery of the BESS, or supplies to the household and charges the battery of the BESS.

17 . The energy coupling system according to claim 16 , wherein the one or more processors are further configured to:

after controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid in response to the energy capacity of the battery of the BESS dropping below the first energy capacity value, continue to monitor the energy capacity of the battery of the BESS; and

in response to the energy capacity of the battery of the BESS exceeding a second energy capacity value, control the AC-to-AC converter to stop supplying the generated AC power to the household electricity grid, the second energy capacity value being greater than the first energy capacity value.

18 . The energy coupling system according to claim 17 , wherein when controlling the AC-to-AC converter to supply the generated AC power to the household electricity grid, the one or more processors are further configured to:

obtain a target output power for the generated AC power outputted from the AC-to-AC converter;

determine whether the actual output power outputted from the AC-to-AC converter is greater or smaller than the target output power;

in response to the actual output power being greater than the target output power, control the AC-to-AC converter to reduce the actual output power to being equal to the target output power; and

in response to the actual output power being smaller than the target output power, control the AC-to-AC converter to repeatedly increase the actual output power by an incremental power step until a difference between the target output power and the actual output power is smaller than the incremental power step.