Control of distributed generation systems to mitigate load and line imbalances

Modern distributed generation systems consist of various types of electrical energy sources such as photovoltaics, wind turbines and gas-fired micro-turbines providing utility grade AC power using a three-phase inverter interface. Although they are currently used as utility alternatives for energy sources, they are capable of maintaining conformance of voltage to stringent power quality standards such as the ITI/CBEMA (Information Technology Industry/Computer & Business Equipment Manufacturers´ Association) curves, and hence are of additional value to customers. This paper investigates control of distributed generation systems to mitigate imbalances due to load conditions and voltage sags from system faults. It presents a unified controller that regulates the terminal voltage of sensitive loads under island mode and power flow in the grid-connected mode