Microstrip Antennas (MSAs) are widely used because of their compat ibility with integrated circuits. However, narrow bandwidth is a limi tation and various methods like incorporation of slots and additional resonators are adopted to increase the bandwidth. Among these, the slot technique is simple and straightforward in enhancing the bandwidth. In the paper, “Two Element Rectangular Microstrip Array Antenna for X and Ku Band Operation”, by B Suryakanth and S N Mulgi, a novel design is presented for dual band operation, one at X and the other at Ku band of frequencies. From the detailed experimental study, it is concluded that the dual band operation of antenna operating at two different bands of frequencies is possible by constructing a two element slot loaded rectangular MSA comprising an H slot in the ground plane.

Radio Frequency Identification (RFID), based on wireless radio communication
technology, is used for tagging and identifying stationary or mobile objects with a special antenna device called RFID reader. The reliability of an RFID system depends on the designed frequency of operation and the surrounding medium. The paper,“An Experimental Study of the Effects of Different Mediums on the Performance of RFID System”, by Sudip Dogra, K M Rajanna, Joyashree Bag and Subir Kumar Sarkar, deals with the experimental investigation of various types of tags under different intervening mediums. The detectability and the range of the tags are measured with different intervening mediums also by keeping the tags at detectable range at various angles. The effect of different mediums on the detectability and range of tags is also studied.

Flexible AC Transmission System (FACTS) devices, based on power electronics
components, are being used in the electric power systems for controlling and optimizing the flow of electrical power in the transmission line. Unified Power Flow Controller (UPFC) is one such FACTS device which is used to improve the steady-state and dynamic performance. In the paper, “Analysis of Reactive Power Compensation Using Unified Power Flow Controller by a New Conduction Angle Controller”, the authors S Baskar and N Kumarappan propose a new conduction angle control technique in the inverter and analyze the performance by mathematical simulation. The operating performance of UPFC is demonstrated on Single Machine Infinite Bus (SMIB) transmission line system. The study shows that the proposed UPFC controller is capable of improving the voltage profile and real and reactive power compensation in the power system.

Optimal Power Flow (OPF) deals with the operation of a power system to meet a specific objective under constraints dictated by the electrical network. Various techniques like Non-Linear Programming (NLP), Linear Programming (LP) and Quadratic Programming (QP) are used for optimization. But these methods suffer from certain drawbacks, such as insecure convergence, algorithm complexity and weak handling of qualitative constraints. Particle Swarm Optimization (PSO) technique can be used to remove these drawbacks. In the paper, “Security Constrained Optimal Power Flow Using Particle Swarm Optimization”, by S Manoharan and A Marimuthu, the solution of the OPF problem with security constraints is studied with the objective of minimizing the overall operating cost while satisfying the power flow equations and system security. An algorithm is proposed and tested on an IEEE 30 bus system for fuel cost minimization with constraints on the real power generation, reactive power generation and bus voltage limits.

Congestion in the modern deregulated power system operation causes overburdening of the resources and may lead to stability problems. Congestion management tools help in minimizing the ill-effects. In the paper, “Congestion Management in Distribution Lines”, by P K Satpathy, Pradyumna Kumar Sahoo, Sagarika Nath and Snigdha Mishra, a novel congestion management scheme has been applied to a practical distribution network in the state of Orissa.

Among renewable energy sources like solar, wind, biomass, tidal and OTEC, Solar Photovoltaic (SPV) energy generation has gained popularity because of the simplicity, and low maintenance cost. A review of the different topologies in the SPV-diesel hybrid power generating systems is presented in the paper, “Latest Trends in SPV-Diesel Hybrid Power Generation System”, by Iranna Korachagaon. The author analyzes the effect of design values for the hybrid systems parameters like panel size, battery size, DG set size and the inverter size and suggests that parallel topology has improved efficiency advantages over series topology.

-- MSR Murty
Consulting Editor