C Vyjayanthi

Optimal Reactive Power Dispatch based on Voltage Stability Criteria in a Large Power System with AC/DC and FACTs Devices

An algorithm for optimal allocation of reactive power in AC/DC system using FACTs devices, with an objective of improving the voltage profile and also voltage stability of the system has been presented. The technique attempts to utilize fully the reactive power sources in the system to improve the voltage stability and profile as well as meeting the reactive power requirements at the AC-DC terminals to facilitate the smooth operation of DC links. The method involves successive solution of steady-state power flows and optimization of reactive power control variables with unified power flow controller (UPFC) using linear programming technique. The proposed method has been tested on a real life equivalent 96-bus AC and a two terminal DC system under normal and contingency conditions.

Optimal placement of Distributed Generation for a projected load increase using Relative Electrical Distance approach

There is a lot of pressure on all the developed and second world countries to produce low emission power and Distributed Generation (DG) is found to be one of the most viable ways to achieve this. DG generally makes use of renewable energy sources like wind, micro turbines, photovoltaic, etc., which produce power with minimum green house gas emissions. While installing a DG it is important to define its size and optimal location enabling minimum network expansion and line losses. In this paper, a methodology to locate the optimal site for a DG installation, with the objective to minimize the net transmission losses, is presented. The methodology is based on the concept of Relative Electrical Distance (RED) between the DG and the load points. This approach will help to identify the new DG location(s), without the necessity to conduct repeated power flows. To validate this methodology case studies are carried out on a 20 node, 66kV system, a part of Karnataka Transco and results are presented.

Evaluation of charges for power transmission and losses in bilateral power contracts

The paper presents a method for transmission loss charge allocation in deregulated power systems based on Relative Electrical Distance (RED) concept. Based on RED between the generator and load nodes and the predefined bilateral power contracts, charge evaluation is carried out. Generally through some power exchange mechanism a set of bilateral contracts are determined that facilitate bilateral agreements between the generation and distribution entities. In this paper the possible charges incurred in meeting loads like generation charge, transmission charge and charge due to losses are evaluated. Case studies have been carried out on a few practical equivalent systems. Due to space limitation results for a sample 5 bus system are presented considering ideal load/generation power contracts and deviated load/generation power contracts. Extensive numerical testing indicates that the proposed allocation scheme produces loss allocations that are appropriate and that behave in a physically reasonable manner.

Integration of PV and battery system to the grid with power quality improvement features using bidirectional AC-DC converter

Grid integration with Photo Voltaic (PV) and Battery energy conversion system focusing on two aspects namely (i) multi-functional features of a bidirectional AC-DC converter working as interface between the PV & battery pack and AC grid sytem, (ii) MPPT tracking performance of boost DC-DC converter with less current ripple are presented in this paper. The PV side Boost Converter is controlled by Perturbation & Observation (P&O) MPPT algorithm to extract the maximum power from the variable solar irradiation. This paper uses an “Opposed current half bridge” type inverter with hysteresis current controller, adopted to ensure desired power quality, and can also supply sinusoidal current at unity power factor. The considered control scheme provides with the desired power flow between PV Panel, battery energy storage system (BESS) and utility grid based on the given reference settings. This model is tested for a hybrid PV Energy Conversion System simulated in MATLAB/SIMULINK for various load cases.