Polamraju. V. S. Sobhan

The present investigation explores the unsteady magnetohydrodynamic (MHD) free convective oscillating flow of an optically thin incompressible viscous fluid embedded in two parallel porous walls under the influence of an externally applied transverse magnetic field with a chemical reaction. The radiative heat flux and heat absorption effects are considered. The governing equations are solved for the velocity, temperature, and concentration distributions making by making use of the Laplace transformation methodology. The impacts of a combined of relevant flow parameters on concentration, temperature, and velocity distribution are discussed with pertinent non-dimensional parameters. The analytical solutions for the governing equations are found by utilization of Laplace transformation methodology. The velocity, temperature and concentration profiles are analyzed. The expression for the velocity, the concentration, the shear stress and the rate of heat and mass transfer are derived and are analysed for different variations of the governing parameters.

Traditional MLIs face several challenges, such as complex configurations, intricate switching control, difficulty in generating gate pulses, a large number of components, and high voltage stress on semiconductors. Additionally, increasing the number of voltage levels tends to raise the device count, which can add to the system's complexity, cost, and, in some cases, reduce reliability. In this paper, a new multilevel inverter (MLI) incorporating switched capacitors for improved performance is proposed. The proposed single source quadruple boost nine‐level inverter (SS‐QBNLI) topology addresses these issues by generating a nine‐level output voltage using only 10 switches, 1 diode, and 2 capacitors. Notably, the inverter achieves a voltage gain of four times the input. The capacitors are self‐balanced without requiring any external balancing circuitry. A simple pulse‐width modulation (PWM) technique based on logic gates is employed to ensure balanced capacitor operation. This approach also reduces the number of switches and minimizes voltage stress, while providing built‐in fault tolerance. The paper presents a detailed comparison with other related topologies. Simulations are conducted in MATLAB/Simulink under various conditions to validate the performance. Finally, the ability of the proposed inverter to achieve voltage boosting is experimentally confirmed from a laboratory prototype.

Motors working in extreme conditions such as ultra high and low temperatures, high contamination, high purity etc. require high maintenance of mechanical bearings and the regular lubrication. Hence there is a need of a motor without mechanical bearings and lubrication in addition to simple in control and less maintenance. There by, bearingless motors (BLMs) gain more attention. The bearingless switched reluctance motor’s (BLSRM) is simple in construction and economical in addition to high speed capacity and high torque to inertia ratio. The magnetic nonlinearity arising due to double salient structure makes rotor eccentric displacement control and speed regulation complicate and needs robust control methodology such as sliding mode control (SMC) which has integrity, high certainty and rapid dynamic response when compared to typical controllers. Sliding mode can be realized with distinct classical reaching laws. This paper presents design and implementation of a SMC for a 12/14 BLSRM and the dynamic performance is endorsed by simulation using Matlab software.

The bearingless switched reluctance motor (BLSRM) is emerging as an attractive option for modern industrial applications because of the features, such as compact size, lubrication and seal free performance, long lifeand ability to rotate at very high speed and high power. The control approach is extremely fundamental to a steady operation because of itshighly nonlinear, multi variable and open loop unstable nature. This paper presents a single neuron based rotor suspension control of a 12/14 Hybrid Pole BLSRM with autonomous rotation and suspension poles. This hybrid pole structure produces the suspension force linearly with respect to rotor position and independent of the torque characteristics. Implementation of a non model based Single neuron adaptive PID Controller by avoiding the modeling complexity is proposed. Experimental results demonstrate that the proposed controller maintains the rotor in the center position as well as the speed tracking and disturbance elimination performances independently.

Now-a-days to ensure power continuity and system’s reliability the protection system is to be designed properly for distribution systems to handle the faults to avoiding the damage to the equipments and to the service engineers. Different types of relays with different working principles are used to detect different types of faults in the system. In order to avoid mal operation of relays, proper coordination is to be carried out. The objective of this paper is to maintain the relay coordination as well as to decrease the working time of relays by optimizing the values of time dial setting (TDS) using linear programming problem technique (LPP). The inequality constraints guarantee the coordination margin for each primary or backup relay pairs having a fault very close to the primary relay. Simulation is carried out on a IEEE 15 bus balanced radial distribution system with 3 different types of relays namely standard inverse, extremely inverse and very inverse relay and the results are presented and analyzed.

Voltage instability has become a serious threat to the operation of modern power systems. Load shedding is one of the effective countermeasures for avoiding instability. Improper load shedding may result in huge technical and economic losses. So, an optimal load shedding is to be carried out for supplying more demand. This chapter implements bat and firefly algorithms for solving the optimal load shedding problem to identify the optimal amount of load to be shed. This is applied for a multi-objective function which contains minimization of amount of load to be shed, active power loss minimization, and voltage profile improvement. The presence of with and without static VAR compensator (SVC), thyristor-controlled series capacitor (TCSC), and unified power flow controller (UPFC) on load shedding for IEEE 57 bus system has been presented and analyzed. The results obtained with bat and firefly algorithms were compared with genetic algorithm (GA) and also the impact of flexible AC transmission system (FACTS) devices on load shedding problem has been analyzed.

In this chapter a multi objective optimal power flow (OPF) is obtained by using latest Metaheuristic optimization techniques BAT search algorithm (BAT), cuckoo search algorithm (CSA) and firefly algorithm (FA) with Unified power flow controller (UPFC). UPFC is a voltage source converter type Flexible Alternating Current Transmission System (FACTS) device. It is able to control the voltage magnitudes, voltage angles and line impedances individually or simultaneously. To enhance the power system performance, the optimal power flow has been incorporated UPFC along with BAT algorithm, cuckoo search algorithm and firefly algorithm based multi objective function comprising of two objectives those are total real power loss and the fuel cost of total real power generation. The BAT algorithm, cuckoo search algorithm and firefly algorithm based OPF has been examined and tested on a 5 bus test system and modified IEEE 30 bus system without and with UPFC. The results obtained with BAT algorithm, cuckoo search algorithm and firefly algorithms are compared with Differential Evaluation (DE).