Power quality improvements for LV networks

In order to increase the capacity of the existing Low Voltage grid, one solution is to increase the nominal residential network voltage from 230 V to 300 V, which is easily accommodated within the voltage rating of existing infrastructure such as cabling. A power electronic AC-AC converter would then be used to step the voltage back down to 230 V at an individual property. Such equipment could also be used to provide power quality improvements on both the utility and customer side of the converter depending on its topology. This paper provides an overview of a project which is looking at the development of such a device. The project is being carried out in collaboration with the local UK, Distribution Network Operator (DNO).

High efficiency SiC AC chopper for LV networks

A proposal to increase the existing residential LV grid voltage from 230 V has been made in order to increase existing network capacity. A power-electronic AC-AC converter is then used to provide 230 V at each property. Several constraints such as temperature rise at the converter location lead to a converter design requiring very high efficiency. In this paper results from a recent feasibility study in terms of LV network capacity increase are presented along with the design and testing of a SiC based 1 kW, AC/AC prototype module, which forms the basis of a much larger 15 kW multi-module converter.

Connection design without accurate LV feeder load data:an argument for LV monitoring

Since privatisation, maintenance of DNO LV feeder maximum demand information has gradually demised in some Utility Areas, and it is postulated that lack of knowledge about 11kV and LV electrical networks is resulting in a less economical and energy efficient Network as a whole. In an attempt to quantify the negative impact, this paper examines ten postulated new connection scenarios for a set of real LV load readings, in order to find the difference in design solutions when LV load readings were and were not known. The load profiles of the substations were examined in order to explore the utilisation profile. It was found that in 70% of the scenarios explored, significant cost differences were found. These cost differences varied by an average of 1000%, between schemes designed with and without load readings. Obviously, over designing a system and therefore operating more, underutilised transformers becomes less financially beneficial and less energy efficient. The paper concludes that new connection design is improved in terms of cost when carried out based on known LV load information and enhances the case for regular maximum feeder demand information and/or metering of LV feeders. © 2013 IEEE.