Ambarnath Banerji

Microgrid: A review

A paradigm shift is evolving for the way electrical power is being generated from the traditional concept of centralized large generators to small generators connected to the distribution system powered by non conventional and renewable sources. These small generators were primarily for back up and were not synchronized to the grid. A trend is being observed to change the role of these distributed generations from back up to primary source of electricity in the form of Microgrid. The paper discusses the effectiveness of the Microgrid in a distribution system and presents a comprehensive review of the Microgrid. Various architecture and control schemes of the Microgrid are reviewed. The use of combined heat and power (CHP) system to enhance the overall efficiency of the power system is discussed. The paper aims at providing a broad perspective on the state of art of the Microgrid to the researchers and application engineers dealing with power quality aspects and Microgrid. The classified manner in which the references are presented in this paper will serve them as quick and useful reference.

Enhancing Quality of Power to Sensitive Loads With Microgrid

The paper discusses the effectiveness of the MicroGrid (MG) in a distribution system. Combined heat and power (CHP) system has been used to enhance the overall efficiency of the power system. Microturbines have been used for CHP operation in this paper. The various methods of controls of the MG are also discussed. A simple and low cost model for MG based on frequency droop control for active power generation, has been proposed. The proposed model can be used in plug and play mode of operation of the MG. The model has been simulated on the MATLAB platform. Performance of the model has been studied under grid connected and under islanded condition.

Wireless transfer of power: Status and challenges

Wireless power transmission systems has revolutionized the transmission of power in various application. The concept has gained momentum recently. This work presents an exhaustive insight and detailed discussion on the components of a systems having Wireless Power Transfer (WPT) and the various techniques used for its implementation. The use of WPT in various fields such as medical, defense etc. have been looked into. The aim of the present work is to provide a broad based perspective on the present state of art of the WPT to the researchers and application engineers dealing with wireless transfer of power. The references are presented in a classified manner which will serve the researchers as a quick and useful bibliography. Experiments are also conducted in laboratory to determine the extent of inductive coupling between two coils. This paper presents a comparison of experimental data obtained with both axial and parallel coupling under changing conditions.

Enhancement of stability of autonomous rural grid

Renewable energy potentials available at rural locations are often harnessed using induction generators. These generators are connected in parallel to form an autonomous local grid, to improve the quality of power supply to the consumers. A DSTATCOM is connected in shunt to the autonomous grid to compensate the loads and to provide the required reactive power of induction generators under loaded condition. The DSTATCOM also enhances the power quality of the autonomous grid by providing reactive power to stabilize the voltage under a fault condition. Further, any deficiency of power in autonomous grid is leveled by a BESS (Battery Energy Storage System) used with the DSTATCOM. The paper simulates the autonomous grid along with a DSTATCOM on a MATLAB platform under different load and fault conditions to study the stabilization of the voltage and frequency of the autonomous rural grid.

Dual Delta Bank TCR for Harmonic Reduction in Three-Phase Static Var Controllers

The conventional “Delta” connected thyristor-controlled reactor (TCR) bank used for static var compensation and other applications is proposed to be split into two identical “Delta” banks each having kvar capacity half of the total TCR capacity. The study presented shows that such combination of two identical “Delta” connected reactor banks, one with phase switching by thyristors and the other with line switching thyristor arrangement can effectively reduce the harmonic generation of the TCR. Since both the three-phase banks are connected in delta, the zero sequence triplen harmonics generated due to phase control of thyristors remain trapped inside the delta, thus reducing the harmonic injection into the power system. Further, some other major characteristic harmonics are also minimized in the TCR line current. Thus, the proposed TCR yields a low current THD which meets the requisite harmonics standards and it can therefore be used as an economic solution for reactive power control over a reasonable range in high power grid without using any external harmonic filter or special phase shifting transformer. This paper describes in detail the modeling, analysis, and performance assessment of the proposed scheme. Simulation results are furnished to evaluate the output characteristics of the scheme under varying operating conditions. Finally, experimental results are presented, which proves the theoretical proposition.

Harmonic Cancellation in a Three-Phase Thyristor Controlled Reactor Using Dual Banks

A three-phase three-wire thyristor controlled reactor (TCR) topology is presented comprising of two reactor banks, involving simultaneous firing angle control of both banks having maximum kVAr in the ratio of 60:40. The first reactor bank is “Δ” connected and has phase switching whereas the second reactor bank is either “Δ” or equivalent “Y” connected with line switching. Such an arrangement prevents the triplen harmonics from entering into the supply system and some major characteristic harmonics can also be eliminated from the TCR line current due to the selection of the ratings of the two reactor banks. Thus, without using any additional filters or phase shifting transformer, this scheme enables reactive power control with a low current total harmonic distortion (THD) over a reasonable range of control, meeting requisite harmonics standards. Simplicity in construction and operational requirements of the proposed topology makes it a viable and cost effective solution. Its modeling, analysis, and performance assessment are presented. Simulation and experimental results support the theoretical proposition.

A New Harmonic Reduced Three-Phase Thyristor-Controlled Reactor for Static VAr Compensators

A new thyristor-controlled reactor scheme is presented in this paper, in which the total bank is split into one Δ- and one Y-connected reactor bank with the addition of a low-rating zig-zag autotransformer, instead of the conventional scheme using a Δ-connected reactor bank with a harmonic current filter. This arrangement prevents the triplen harmonics generated by the Y bank from entering into the supply system and at the same time, the combination results in cancellation of some major characteristic harmonics from the source current. Thus, without using any additional filters or phase-shifting two-winding transformer, this scheme facilitates reactive power control over a wide range and also meets the requisite harmonics standards. The scheme is simple and provides a cost-effective solution to the VAr compensation problem. Simulation and experimental results are provided to validate the proposed concept.

A rural autonomous grid delivering quality power to its loads

Renewable energy potential in the form of wind or micro hydro are available in abundance at rural locations far away from city habitat. To harness this green energy the rugged induction generator has come up as a viable option. However, induction generator has change in reactive power requirement with change in load. This dynamic reactive power requirement is proposed to be met by a DSTATCOM and thereby achieve voltage regulation, load balancing and harmonic elimination. Further these small generators can provide full benefit to rural customers if they are connected on a grid. An autonomous rural grid with induction generators in parallel is proposed for reliable supply of power and to harness the benefits of the grid. A rural autonomous grid has been simulated in this paper using induction generators and a DSTATCOM on a MATLAB platform and study is made regarding the performance of the rural autonomous grid under linear and nonlinear loads and under varying load conditions.

Optimal placement of DG using Swarm intelligence approach in distributed network: Status & challenges

In recent years, the significance of distributed generation has increased rapidly in distribution system. The prominent goal of DG placement is to measure the optimized location, type and sizes of DGs for getting best efficiency by maximizing or minimizing different constraints. This work investigates the recent research in the field of Swarm intelligence based optimal DG placement. Swarm intelligence is mainly categorized into Ant Colony Optimization & Particle Swarm Optimization. To get optimal solution, various researchers considers different constraints to get their solution. This article surveys those research works showing recent trends of Optimal DG Placement using Ant Colony Optimization & Particle Swarm Optimization.

Enhancement of voltage stability of autonomous wind power generation system using DSTATCOM

Wind as renewable energy potential is abundantly available at remote locations. This can be harnessed by using the rugged induction generator. However there is a dynamic requirement of reactive power as the load changes. A DSTATCOM has been proposed in this paper to cater for the dynamic requirement of the reactive power for the Induction generator with the change in load and to stabilize the terminal voltage of the wind generator under fault conditions. The paper simulates the autonomous system consisting of wind turbine, induction generator along with a DSTATCOM on a MATLAB platform and studies the stabilization of the voltage under varying load and different fault conditions.