Patent ID: 8780593

Claim:
A power compensation apparatus which is used in a renewable energy system, the power compensation apparatus comprising: a plurality of converter modules positioned between any two phases of a three-phase alternating current (AC) electrical grid, wherein the converter module comprises a plurality of inverter circuits connected in series, and each of the inverter circuits has: an energy storage unit for providing a direct current (DC) voltage; a capacitor connected to the energy storage unit; and an H-bridge circuit connected to the capacitor in parallel for converting the DC voltage from the energy storage unit into an AC voltage, wherein the H-bridge circuit has a first bridge arm and a second bridge arm, and a first output terminal on the first bridge arm is electrically connected to one of any two phases of the electrical grid through a coupling device, and a second output terminal on the second bridge arm is connected in series to another inverter circuit adjacent to the inverter circuit, wherein, the converter modules are connected in a delta connection; wherein, when an output voltage of the converter module is higher than a voltage of the electrical grid, the converter module outputs inductive reactive power; when the output voltage of the converter module is lower than the voltage of the electrical grid, the converter module outputs capacitive reactive power; and when the voltage of the electrical grid drops, the power compensation apparatus provides reactive power compensation to keep the voltage of the electrical grid stable, and provides active power regulation so as to keep a frequency of the electrical grid stable.