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This paper presents the transient performance of a series-compensated three-phase self-excited induction generator (SEIG) feeding a dynamic load such as a three-phase squirrel-cage induction motor (IM). Mathematical modeling and simulation study of SEIG and an induction motor (SEIG-IM) combination is carried out using MATLAB/Simulink. An exhaustive experimental study is conducted using a Mawdsley's generalized machine operating as a SEIG and a three-phase squirrel-cage IM as the dynamic load. The simulated results are compared with the experimental results under various operating conditions of the SEIG such as the following: 1) its voltage and current buildup at no-load; 2) switching of a three-phase squirrel-cage IM to the SEIG terminals without series-compensating capacitors (resulting failure to start an IM); and 3) switching on the same motor with the series capacitors (resulting in successful starting of the IM). A sudden switching of the IM as a dynamic load on the SEIG without the series compensation causes severe transients in electrical and mechanical variables of the SEIG and due to large starting current requirement of the IM, there is a collapse of the terminal voltage of SEIG. However, the use of series compensation in short-shunt configuration of SEIG results in the successful starting of the IM with an improved voltage regulation of SEIG. The phenomenon of subsynchronous resonance (SSR) is observed due to the large variations in the impedance of the SEIG-IM combination and the presence of series capacitors. It causes low frequency oscillations in the IM stator voltages, currents, and its speed. The SSR phenomenon restricts the IM to attain the rated speed. A detailed study of the SEIG-IM system is made to select proper combination of shunt and series capacitors to avoid the SSR phenomenon.

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A phase-locked loop (PLL) plays an integral part in synchronisation circuits and is immensely used in grid-connected systems, active filters, and uninterrupted power supplies. A number of these circuits based on synchronous reference frame and its modifications, second-order generalised integrator, enhanced PLL (EPLL) have recently been reported in literature. This article proposes an adaptive version of EPLL whose gain adjusts automatically with the variation of error. Adaptive EPLL (A-EPLL) is developed for positive sequence extraction of load current and its performance is tested for active filter operation. A PV system is also connected at the DC link of the shunt active power filter (SAPF) and the developed controller is tested under dynamic load changes. The complete control technique is tested for harmonics reduction, load balancing, and power balance between grid, load, and photovoltaic (PV) source. Detailed experimental results showing a new adaptive PLL for load compensation are illustrated here.

Application of particle swarm optimisation (PSO) in efficiency optimisation of vector controlled surface mounted permanent magnet synchronous motor (PMSM) drive is presented in this study. Analytical expressions for the controllable electrical loss in PMSM are derived and optimised through control of direct axis (d-axis) stator current, according to the desired speed of operation and load torque. The optimal value of d-axis current has been obtained through analytical method as well as through PSO. The motor efficiency is maximised by using the optimal d-axis current to minimise the air gap flux, resulting in reduction of the core losses, especially at light load conditions. The robustness of the efficiency optimisation algorithms are demonstrated through parametric sensitivity analysis. Implementations of efficiency optimisation algorithms are carried out in Matlab and the performance of PMSM drive is described under steady state as well as transient operating conditions. The effect of efficiency optimisation algorithms in different region of operation of PMSM such as constant speed-variable load torque and constant torque-variable speed modes are described.

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