An Overview on Power Quality Issues and Control Strategies for Distribution Networks With the Presence of Distributed Generation Resources (original) (raw)
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Electric utilities and end users of electric power are becoming increasingly concerned about meeting the growing energy demand. Seventy five percent of total global energy demand is supplied by the burning of fossil fuels. But increasing air pollution, global warming concerns, diminishing fossil fuels and their increasing cost have made it necessary to look towards renewable sources as a future energy solution. Since the past decade, there has been an enormous interest in many countries on renewable energy for power generation. Renewable energy source (RES) integrated at distribution level is termed as distributed generation (DG). The utility is concerned due to the high penetration level of RES in distribution systems as it may pose a threat to network in terms of stability, voltage regulation and power-quality (PQ) issues. Therefore, the DG systems are required to comply with strict technical and regulatory frameworks to ensure safe, reliable and efficient operation of overall net...
2019
1Assi. Prof., Dept of Electrical Engineering, DMIETR, Wardha, Maharashtra, India 2Assi. Prof., Dept of Electrical Engineering, DMIETR, Wardha, Maharashtra, India ---------------------------------------------------------------------***---------------------------------------------------------------------Abstract –. Power quality is the measure, analysis and improvement of bus voltage usually load bus voltage to maintain that voltage to be sinusoidal at rated voltage and frequency. It is the collections of all electrical networks as the ability of system equipment to perform satisfactorily without discontinuity. Power quality problem occurs when the alternating voltage sine wave is distorted. This paper describes how to deal with effect of power quality problems along with its solutions. Even it is benefited for the suppliers, distributors and consumers of electricity.
Power Quality Improvement at Distribution Level for Grid Connected Renewable Energy Sources
The non-linear load current harmonics may result in voltage harmonics and can create a serious PQ problem in the power system network. Active power filters (APF) are extensively used to compensate the load current harmonics and load unbalance at distribution level. This results in an additional hardware cost. However, in this project it has incorporated the features of APF in the conventional inverter interfacing renewable with the grid, without any additional hardware cost. Here, the main idea is the maximum utilization of inverter rating which is most of the time underutilized due to intermittent nature of RES. The grid-interfacing inverter can effectively be utilized to perform the four important functions they are to transfer active power harvested from the renewable resources (wind, solar, etc.), load reactive power demand support, current harmonics compensation at PCC and current unbalance and neutral current compensation in case of 3-phase 4-wire system. Moreover, with adequate control of grid-interfacing inverter, all the four objectives can be accomplished either individually or simultaneously. The PQ constraints at the PCC can therefore be strictly maintained within the utility standards without additional hardware cost. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies
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This thesis deals with voltage drop characterization of transmission systems by using power electronics circuits supplied from embedded generation. Many grids connected power electronic systems, such as STATCOMs, UPFCs, and distributed generation system interfaces, used voltage source inverters (VSI) connected to the supply network through a filter. This filter, typically a series inductance acts to reduce the switch harmonics entering the distribution network an alternative filter is an LCL network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power application. However, systems incorporating LCL filters require more complex control strategies. This dissertation proposes a robust strategy for regulating the grid current connected via an LCL filter. The strategy integrates an outer loop grid current regulator with inner capacitor current regulation to stabilize the system. Asynchronous farm PI current regulation strategy is used for the outer grid current control loop. Linear analysis, simulation and experimental results are used to verify the stability of the control algorithm across a range of operating conditions and finally expressions for "harmonic impedance" of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system.
Impacts of Renewable Sources on Power Quality in Distribution Systems
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This paper analyzes the influence of renewable sources (RS) on voltage quality in MV networks and summarizes problems considered of general interest relating to the power quality of dispersed generation. We are interested in voltage fluctuations, flicker, harmonic distortion, interharmonic distortion, and the effect of dispersed generation on ripple control signals. The influence of DG on voltage stabilization, line losses, and short circuit impedance are also investigated. A basic analysis of the possibility and effectiveness of using a parallel Active Filter (AF) to compensate for the constant-speed wind turbine (WT) flicker, reactive power, and terminal voltage variation is presented too.
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