The growth of building integrated photovoltaic (BIPV) systems in low-voltage (LV) networks has the potential to raise several technical issues, including voltage unbalance and distribution system efficiency. This paper proposes an energy storage system (ESS) for mitigating voltage unbalance as well as improving the efficiency of the network. In the study, a power system simulation tool, namely PSCAD, is used to model two generic LV networks, BIPV systems and an ESS in order to simulate the performance of the networks with various levels of BIPV penetrations. A control algorithm is developed and implemented in the energy storage model in order to study the ability of the ESS to mitigate network voltage unbalance and reduce losses. Experimental studies are carried out in the experimental small-scale energy zone to investigate the effectiveness of the energy storage system under various levels of PV penetration and load conditions. The simulation and experimental studies carried out clearly show the effectiveness of the ESS in reducing the voltage unbalance factor and improving the efficiency of the two networks considered.

Numbers of incentives were offered by Malaysian government to encourage the growth of renewable energy in meeting the Tenth Malaysian Plan (from 2011 to 2015) target of 98 MW which contributes 5.5% of the total electricity generation. It becomes increasingly important to understand the technical challenges facing high penetration of distributed generation (DG), especially for photovoltaic (PV) system. With many larger PV installations in low voltage distribution networks (LVDN) coming soon, several issues may arise such as voltage unbalance, voltage regulation, voltage rise, cable and transformer thermal limits and network losses inLVDN. This paper presents a technique to mitigate the voltage unbalance in LVDN with a high penetration of PV system by using a controllable Energy Storage Unit (ESU). Investigations are carried out in the experimental Small-Scaled Energy Zone (SSEZ)

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.