Intelligent voltage dip mitigation in power networks with distributed generation

Includes bibliographical references.The need for ensuring good power quality (PQ) cannot be over-emphasized in electrical power system operation and management. PQ problem is associated with any electrical distribution and utilization system that experiences any voltage, current or frequency deviation from normal operation. In the current power and energy scenario, voltage-related PQ disturbances like voltage dips are a fact which cannot be eliminated from electrical power systems since electrical faults, and disturbances are stochastic in nature. Voltage dip tends to lead to malfunction or shut down of costly and mandatory equipment and appliances in consumers’ systems causing significant financial losses for domestic, commercial and industrial consumers. It accounts for the disruption of both the performance and operation of sensitive electrical and electronic equipment, which reduces the efficiency and the productivity of power utilities and consumers across the globe. Voltage dips are usually experienced as a result of short duration reduction in the r.m.s. (r.m.s.- root mean square) value of the declared or nominal voltage at the power frequency and is usually followed by recovery of the voltage dip after few seconds. The IEEE recommended practice for monitoring electric power quality (IEEE Std. 1159-2009, revised version of June 2009), provides definitions to label an r.m.s. voltage disturbance based upon its duration and voltage magnitude. These disturbances can be classified into transient events such as voltage dips, swells and spikes. Other long duration r.m.s. voltage variations are mains failures, interruption, harmonic voltage distortion and steady-state overvoltages and undervoltages. This PhD research work deals with voltage dip phenomena only. Initially, the present power network was not designed to accommodate renewable distributed generation (RDG) units. The advent and deployment of RDG over recent years and high penetration of RDG has made the power network more complex and vulnerable to PQ disturbances. It is a well-known fact that the degree of newly introduced RDG has increased rapidly and growing further because of several reasons, which include the need to reduce environmental pollution and global warming caused by emission of carbon particles and greenhouse gases, alleviating transmission congestion and loss reduction. RDG ancillary services support especially voltage and reactive power support in electricity networks are currently being recognized, researched and found to be quite useful in voltage dip mitigation

Single-phase power generation employing VFC for standalone three-phase doubly wound asynchronous generator

Dwag (DOUBLY Wound Asynchronous Generator) is prominent choice in variable speed energy conversion system due to its improved conversion efficiency and reduced rating converters [1]. In general, DWAG's are considered suitable choice for large rating installations [2]. To supply rural community located in small pockets and far away from grid utility, standalone energy conversion system fed through renewable energy prime movers such as pico-hydro and wind are gaining its popularity [2]–[3]. For such small scale energy conversion systems, single-phase distribution system is preferred choice to feed such consumers to minimize capital investment. Three-phase isolated asynchronous generator (lAG) has been reported in the literature for such applications [4]–[6]. However, it has been observed that even with a three-phase lAG, utilization of machine rating is not more than 40% [7]. Recently, a topology has been reported for the power generation to feed single-phase loads employing three-phase lAG to optimize the utilization of generating machine [8]. However, when the prime-movers are of variable speed in nature such as a wind turbine, these lAG based generating systems which are controlled for fixed speed operation, do not achieve MPT (Maximum Power Tracking) under varying wind speeds [9]. The lAG for variable speed operation requires two full rating converters [10]. A DWAG with back-back connected partial rating converters at rotor terminals allows variable speed operation of prime-mover to achieve MPT along with regulated stator terminal voltage and its frequency [11]–[16]. In the literature, DWAG based wind power installations have been explored mainly for grid connected WPGS (Wind Power Generation Systems) in large unit ratings [17]–[22]. However, a DWAG has never been explored in the literature for single-phase standalone power generation

New Developments in Renewable Energy

Renewable energy is defined as the energy which naturally occurs, covers a number of sources and technologies at different stages, and is theoretically inexhaustible. Renewable energy sources such as those who are generated from sun or wind are the most readily-available and possible solutions to address the challenge of growing energy demands in the world. Newer and environmentally friendly technologies are able to provide different social and environmental benefits such as employment and decent environment. Renewable energy technologies are crucial contributors to world energy security, reduce reliance on fossil fuels, and provide opportunities for mitigating greenhouse gases. International public opinion indicates that there is strong support for a variety of methods for solving energy supply problems, one of which is utilizing renewable energy sources. In recent years, countries realized that that the renewable energy and its sector are key components for greener economies

Recent Development of Hybrid Renewable Energy Systems

Abstract: The use of renewable energies continues to increase. However, the energy obtained from renewable resources is variable over time. The amount of energy produced from the renewable energy sources (RES) over time depends on the meteorological conditions of the region chosen, the season, the relief, etc. So, variable power and nonguaranteed energy produced by renewable sources implies intermittence of the grid. The key lies in supply sources integrated to a hybrid system (HS)

Full Proceedings, 2018

Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University