Andrew Crossland

Coordination of Multiple Energy Storage Units in a Low-Voltage Distribution Network

A method for the coordination of multiple battery energy storage systems (BESSs) is proposed for voltage control in low-voltage distribution networks (LVDNs). The main objective of this method is to solve over-voltage problems with multiple suitably sized energy storage systems. The performance of coordinated control is compared with noncoordinated control using both a real-time digital simulator and a MATLAB model of a real U.K. LVDN with a high installed capacity of solar photovoltaics. This is used to show that coordinated control is robust and effective at preventing voltage rise problems in LVDNs. The proposed coordinated control scheme is able to use the BESSs more evenly, and therefore reduces the costs of battery replacement to the storage operator in terms of both number of batteries and maintenance visits.

Mechanical to electrical energy conversion in a hybrid liquid-solid dielectric electrostatic generator

The authors are studying the effect of the dielectric choice in electrostatic generators on the energy yield. Despite having high permittivities, solid dielectrics are shown to have a lower performance than is first apparent, due to the effect of the air gap. Liquid dielectrics are found to offer higher overall equivalent permittivities compared to solid dielectrics with air gaps but the conductivity of liquids limits their performance. Experimental work has been conducted using a hybrid generator which incorporates both solid and liquid layers. The solid polyvinylidene fluoride layer is used to limit the conduction between the plates and the liquid dielectric is withdrawn or injected for the necessary change in capacitance. The experimental work has demonstrated a number of design considerations for such generators and is ultimately used to show that energy conversion is possible using this electrostatic generator configuration.