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A novel method of reducing the energy consumption of street lighting using electronic ballasts was simulated on 277 units of 250 W high pressure sodium (HPS) street lights for a month. The design of the electronic ballast is detailed. A control system was utilised to dim the lights at hours of reduced traffic. The energy consumption was compared to that of the conventional system. The electronic ballast operates at a higher frequency and corrects any power distortion in the supply. Together with the light dimming capability, the electronic ballast increased the efficiency of the lighting system resulting in a monthly saving of 10.7 MWh, giving a monthly equivalent carbon dioxide reduction of 6.1 tonnes. In Malaysia, this would translate to a monthly cost saving of 37.7%.

This paper presents the efficiency optimization of a variable speed induction machine (VSIM) using an Optimal Flux Control (OFC). To optimize the efficiency, an approach called as Maximum Torque per Ampere (MTA) algorithm was used to provide the constant optimal flux (COF) during the speed control, where the minimisation of the winding losses is considered along the operation. In this paper, the total power and total power loss during machine motoring is presented. The performance of the proposed OFC design is compared with the conventional open-loop scalar-control (OLSC) method. From the finding, it was found that the COF approach provides better performance than the OLSC in terms of settling time, steadystate error and efficiency.

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