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This paper presents a speed controller using a fuzzy-logic controller (FLC) for indirect field oriented control (IFOC) of induction motor (IM) drives fed by a four-switch three-phase (FSTP) inverter. In the proposed approach, the IM drive system is fed by FSTP inverter instead of the traditional six-switch three-phase (SSTP) inverter for a cost-effective low power applications. The proposed FLC improves dynamic responses and, it is also designed with reduced computation burden. The complete IFOC scheme incorporating the FLC for IM drives fed by the proposed FSTP inverter is built in Matlab/Simulink and, it is also experimentally implemented in real-time using a DSP-DS1103 control board for a prototype 1.1 kW IM. The dynamic performance, robustness, and insensitivity of the proposed FLC with FSTP inverter fed IM drive is examined and compared to a traditional PI controller under speed tracking, load disturbances, and parameters variation, particularly at low speeds. It is found that the proposed FLC is more robust than the PI controller under load disturbances, and parameters variation. Moreover, the proposed FSTP IM drive is comparable with a traditional SSTP IM drive, considering its good dynamic performance, cost reduction and low THD.

A multiobjective framework that optimises the uprating of the line's real-time thermal rating and capacity of battery storage against wind curtailment, network ageing and reliability is proposed. The two enhancements are limited to the accumulated expected amount and duration of wind power losses of each wind farm bus. In the framework, actual conductor properties, line failures due to thermal effects, weather data, battery operation policy and wind farm model are considered. The trade-off of the optimisation criteria, the Pareto front, is solved using the non-sorting genetic algorithm and fuzzy decision-making method. Results show that the conductor maximum allowable temperature affects all the three optimisation parameters, but battery efficiency only affects wind curtailment level.

Battery energy storage systems (BESS), demand response (DR) and the dynamic thermal rating (DTR) system have increasingly played important roles in power grids worldwide. In addition to storing energy, BESS can supply peak demands, thereby reducing the frequency of load interruptions and deferring new asset investments. However, study on the precise BESS sizing (i.e. energy and power ratings) to supply peak demands to improve the security of supply of transmission networks is still lacking. The combined efficacy of BESS, DR and DTR have also never been studied, because their simultaneous deployment has never been considered. The first contribution of this paper is proposing a probabilistic evaluation method to evaluate various combinations of BESS power ratings and energy capacities and determines their impacts on the reliability of transmission networks, in which peak demands are supported by charges stored in BESSs to address the security of supply problem. The second contribution extends the proposed method to examine the effects of deploying BESS alongside DR and DTR. Our results show that the security of power supply improves along with BESS sizing by as much as 37.2%, and that its reliability becomes more significant as its capability grows, with bigger BESS having more detrimental effects towards EENS as it becomes unavailable than smaller BESS does. DTR and DR reduce the requirements of BESS sizing without adversely affecting network reliability.

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The increased integrations of intermittent renewable energy sources into power systems cause more power grid congestions and therefore system operators need more advanced control to relieve this pressure. The dynamic thermal rating (DTR) system is able to increase the thermal constraint and subsequently maximum loading of existing lines. This dynamic rating is achieved through real-time considerations of weather data and it is usually much higher than the traditional static thermal rating system. The operational tripping scheme (OTS), a variant of the wider system integrity protection scheme, also relieves line congestions but it does this by tripping pre-selected generators and this have the unwanted consequence of reducing power adequacy. This paper proposes the novel integration of DTR and OTS, while considering the inherent uncertainties of their sensors based on fuzzy numbers, to avoid unnecessary generation tripping due to conservative line ratings. This novel Fuzzy-DTR-OTS delays the tripping of generations, enhances the adequacy of power supply, improves system security and avoids high risk cascading black out inducing events.INDEX TERMS dynamic thermal rating, SIPS, conductor temperature, wide area monitoring NOMENCLATURE ConstantsConductor heat capacity (J/m ⋅ ℃) Density of air (kg m 3 ⁄ )