Distributed Energy Storage with Real and Reactive Power Controller for Power Quality Issues Caused by Renewable Energy and Electric Vehicles

The integration of renewable energy sources (RE) and electric vehicles (EV) into the low voltage (LV) networks can create a number of power quality issues. RE or EV can cause voltage unbalance and low power factor when it injects or absorbs real power from the network. The energy storage system can be connected to the network to manipulate the power flow from or to those devices with the use of reactive power as a complementary support, hence correcting the voltage unbalance and power factor effectively without wasting any generated energy. To be able to correct the voltage unbalance and power factor effectively under the intermittent power of RE and EV, a novel fuzzy controller is developed and implemented in the energy storage to manipulate the flow of real and reactive power between the energy storage and the network based on the network conditions. The fuzzy controller is able to reduce any voltage excursions with the use of real and reactive power from the energy storage, hence reducing the voltage unbalance and improving the power factor. Numerous experiments have been carried out to verify the effectiveness of the fuzzy controller. The experimental results show that the voltage unbalance and power factors are constantly maintained below the thresholds under the high intermittent power output of the photovoltaic systems.