A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

The present invention relates to a power management system (PMS) for multiple energy storage systems (ESS) that is for integrated management of the system having multiple ESS for controlling a frequency and having a hierarchical control structure. The PMS for ESS comprises: a plurality of ESS; a local management system (LMS) for managing one or more ESS of the plurality of ESS for each local unit; an ESS Controller (ESSC) for general management of the LMS, judging a state of the LMS and determining an output value of one or more ESS in the LMS, and transmitting the determined output value to the respective ESS; and a PMS for general management of the entire system comprising the plurality of ESS, the LMS and the ESSC, judging the state of the entire system and participating in a power grid frequency control market through a grid operator contract, controlling the output of the LMS, and adjusting a control parameter for output control.

A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

An electric power control system for controlling supply and consumption of electric power in a system power supply, a storage battery and an electric power load, said electric power control system including: an estimated value correction unit configured to obtain a difference between a past power control estimated value and a past actual performance value, and to shift a power control estimated value obtained as a result of estimation in a predetermined period to an extent corresponding to said difference, thereby correcting the power control estimated value, wherein said past power control estimated value is a value obtained as a result of estimation performed in a past time relative to said predetermined period, and said past actual performance value is a value obtained as an actual result in the past time; and a power control unit configured to control supply and consumption of electric power in the system power supply, the storage battery, and the electric power load, based on the power control estimated value corrected by the estimated value correction unit.

A system includes a converter configured to be coupled between an energy storage unit and a grid and a control circuit configured to detect frequency and voltage variations of the grid and to responsively cause the converter to transfer power and reactive components to and/or from the grid. The control circuit may implement a power control loop having an inner frequency control loop and a reactive component control loop having an inner voltage control loop. The control circuit may provide feedforward from the inner frequency control loop to the inner voltage control loop to inhibit reactive component transfer in response to a voltage variation deviation of the grid due to a power transfer between the energy storage unit and the grid.

In switching of a microgrid from an isolated operation to an interconnected operation with a power grid, a CEMS server determines a first master DER and slaves based on a master plan and performs master-slave control. When the first master DER goes down, the CEMS server compares remaining capacities of power-storage-type DERs included in a DER group. The CEMS server then determines a DER with the highest remaining capacity as a second master DER among the power-storage-type DERs included in the DER group and performs master-slave control.

A low-voltage circuit in a bidirectional DC-DC converter converts output AC power from a high-voltage circuit to DC power to charge a smoothing reactor and discharge the smoothing reactor, and includes an active snubber circuit including switching elements and each having a backward diode and a snubber capacitor. The snubber capacitor of the active snubber circuit has its one end connected to a drain end of the switching elements and has its other end connected to a node between a center tap of a high-frequency transformer and a smoothing reactor.

A power converting device includes a DC-DC converting circuit, a DC-AC converting circuit, and an insulation detecting circuit. The DC-DC converting circuit is configured to convert a DC input voltage to a DC bus voltage. The DC-AC converting circuit is electrically coupled to the DC-DC converting circuit and configured to convert the DC bus voltage to an AC voltage. The insulation detecting circuit is electrically coupled between the DC-DC converting circuit and the DC-AC converting circuit. The insulation detecting circuit is configured to detect a ground impedance value of the power converting device according to the DC bus voltage.