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International Electronical Committee (IEC) 61850-90-7 is a part of the IEC 61850 series which specifies the advanced functions and object models for power converter based Distributed Energy Resources (DERs). One of its functions, the Voltage/VAR (V/V) control function, is used to enhance the stability and the reliability of the voltage in the distribution system. The conventional V/V function acts mainly for flattening the voltage profile as for a basic grid support function. Currently, other objectives such as the minimization of line loss and the operational costs reduction are coming into the spotlight. In order to attain these objectives, the V/V function and hence the DER units shall actively respond to the change of distribution system conditions. In this paper, the modification of V/V function and new requirements are proposed. To derive new requirements of V/V function, loss minimization is applied to a particle swarm optimization (PSO) algorithm where the condition of voltage constraint is considered not to deteriorate the voltage stability of the distribution system.

POSCO and the Research Institute of Industrial Science and Technology developed a 10-kW superconducting synchronous generator using high-temperature superconducting wire. The generator consists of four-pole racetrack-type superconducting coils using GdBCO wire for rotor and 24 slots copper windings for stator. The rated power of the generator was 10 kW at 600 r/min, and the operating temperature was 30 K by thermosyphon cooling method using liquid neon. The output power was measured when the generator was connected to a vector motor, and the detailed results were discussed in this paper.

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A wind farm is a collection of a few tens or a few hundreds of wind turbine generator installed in close vicinity. There is a need for further research to examine the performance of wind farm and wake models in difficult environments. This paper deals with the modelling of the wake effect in wind farms using real time digital simulator. There are many different models to analyse the wake effect. Jensen model is one of the widely used wake models at the moment. The model is simpler and requires a short time for calculations. Power loss of the modelled wind farm with the wake effect is analysed under the effects of wind direction and the wind speed time delay. The modelling of a wind farm for wake effect simulation is described and some exemplary simulations are also performed to show the influence of wake effect.

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