Squirrel cage induction motor (SQIM) fed by a pulse width modulated voltage source inverter (VSI) is subjected to voltage and current surges. It may cause additional losses in the motor, insulation failure, high bearing current, and electromagnetic interference. To mitigate these problems, sinusoidal LC filter is placed at the ac-side of the VSI. This paper proposes a new methodology to design the filter. In this method, the filter inductance is chosen based on the maximum ripple in the inverter ac-side current and the voltage drop across the filter inductor, and the filter capacitor is chosen based on the steady-state reactive power demand of the SQIM. The effects of the designed filter on the switch current, losses in the drive, temperature of the dc-link capacitor, dv/dt at the motor terminal, stator flux, and air-gap torque of the SQIM are discussed. The performance of the drive with the filters, designed by the proposed method and the standard method, are experimentally tested on a two-level Silicon carbide (SiC) VSI fed SQIM and comparative analysis is carried out. The impact of the designed filter on the drive is also shown when the neutral point of the filter capacitors is connected with the mid-point of the dc-link. The stability of the closed-loop controlled SQIM drive with the proposed filter, and simulation results are presented to verify its performance. Index Terms-Sinusoidal LC filter, squirrel-cage induction motor drive, variable-frequency operation. The following impacts of the filters designed by PM and SM are discussed, and comparative analysis is carried out: 1) The switch current of the VSI and the cumulative power loss in the drive with two filters have been discussed. 2) The effects of the two filters on the dc-link capacitor of the VSI have been discussed.

This paper presents automatic generation control (AGC) of interconnected two equal area thermal system, two equal area hydrothermal System and five unequal area thermal system. Thermal plants have single reheat turbines with generation rate constraints of 3% per minute. The hydro plant in hydrothermal system has electric governor and has generation rate constraints of 270% per minute for raising generation and 360% per minute for lowering generation. A novel classical controller based on Integral and Double Derivative control is used in AGC and its performance is compared to several other classical controllers such as Integral (I), Proportional-Integral (PI), Integral-Derivative (ID) and Proportional-Integral-Derivative (PID) controllers. Integral squared error (I.S.E) and Bacteria Foraging (BF) techniques are used for optimization. Investigations reveal on comparison that Integral (I), Proportional-Integral (PI), Integral-Derivative (ID) orProportional-Integral-Derivative (PID) controllers all provide more or less same response where as Integral -Double Derivative (IDD) controller provides much better response. Further, the controller action can be optimally delayed to provide the best dynamic response.Index Terms-Automatic generation control, bacterial foraging technique, integral plus double derivative controller, speed regulation parameter.

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