4. CO-ORDINATED CONTROL OF GRID CONNECTED PHOTO VOLTAIC REACTIVE POWER AND BATTERY ENERGY STORAGE SYSTEM TO IMPROVE THE VOLTAGE PROFILE OF THE RESIDENTIAL DISTRIBUTION FEEDER

The ever increasing energy demand, along with the necessity of cost reduction and higher reliability requirements, are driving the modern power systems towards distributed generation (DG) as an alternative to the expansion of the current energy distribution systems. In particular, small DG systems, typically with power levels ranging from 1 kW to 10 MW, located near the loads are gaining popularity due to their higher operating efficiencies. Photovoltaic cells (PV), Fuel cells (FC), Batteries, micro turbines, etc. are nowadays the most available DGs for generation of power mostly in peak times or in rural areas. It is desirable that the utilities ensure that the customers are supplied with a high power quality. Among the power quality parameters, voltage profile and Voltage Unbalance (VU) are the major concerns in low voltage (LV) distribution networks. Voltage drop c an be experienced in network peak hours while voltage rise can be experienced in network off – peak hours with high generation and penetration of DG units. The utilities are responsible for keeping the voltage in their network within the standard limits to p revent malfunction of customer devices. Voltage unbalance is more common in individual customer loads due to phase load unbalances, especially where large single –phase power loads are used. Although voltages are well balanced at the supply side, the voltages at the customer ends can become unbalanced due to the unequal system impedances, unequal distribution of single –phase loads or large number of single –phase transformers. Usually, the electric utilities aim to distribute the residential loads equally amo ng the three phases of distribution feeders.