International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 09 | Sep 2024
p-ISSN: 2395-0072
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Optimal designing and parameter selection of voltage source inverter for real-time performance analysis in weak grid and standalone mode Harendra Pal Singh1*, Anurag K. Swami1 1Department of Electrical Engineering
College of Technology, Pantnagar Uttarakhand, 263145, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - This study aims to enhance inverter stability for
measures, and responses under abnormal conditions, have been established, offering valuable guidance for applicationspecific practices, as noted by [2],[3]. Across the globe, widely recognized standards, such as IEEE – 1547 [4], IEC – 61727 [5], IEEE – 929 [6], along with region-specific standards like VDE-AR-4105 (Germany) [7] and RULE-21 (California, USA) [8], play a pivotal role in governing the interconnection of DERs with the grid, ensuring a seamless transition towards cleaner and more sustainable energy systems.
lower-voltage distribution networks by focusing on grid impedance-based stability. Additionally, it suggests considering IEEE Standard-519 when selecting the ideal filter and controller parameters for weak grids. Two techniques are used to improve inverter stability: (A) altering the grid-side inductance, and (B) changing the VSI's output impedance. The goal is to optimize the VSI controller's and filter design's parameters. To obtain the optimized Current Control Loop (CCL) parameters to maintain the Total Harmonic Distortion (THD) level at the Point of Common Coupling (PCC) and ensure VSI stability during parametric uncertainty, ZieglerNichols (ZN), Particle Swarm Optimization (PSO), and a realcoded Genetic Algorithm (GA) are utilized. To validate the effectiveness of the optimized CCL parameters, a real-time simulator, Typhoon HIL, is used to simulate a VSI-based system connected to a weak grid and operating in standalone mode. Various conditions, such as filter inductance variation, grid Short Circuit Ratio (SCR), output power regulation, and sudden load changes in a standalone distribution network, are tested. The VSI-based system's controller model simulation and parameter optimization are performed using MATLAB/SIMULINK with m-files. Regardless of whether the inverter is connected to the grid or not, this paper provides an extensive review of how to select the optimal inverter component parameters and their impact under various realworld conditions
For systems rated at 69 kV and below, IEEE Std. 519 recommends specific limits to ensure the quality of power at the PCC. According to [9], it stipulates that the total harmonic distortion should not exceed 5%, and individual voltage distortion should be within 3%. Additionally, it provides guidelines for limiting the current distortion concerning the short circuit current (Isc) to load current ratio (IL), emphasizing the attenuation of higher-order harmonic components. To gauge the strength of the grid connection, [10] points out that the percentage of current ripples in the inverter output current is a crucial indicator. For weaker grid connections, the standard allows for 0.3% current ripples, while in the case of stronger grid connections, this tolerance can be higher. This approach defines the smoothness of the output current, ensuring compliance with the specified grid connection conditions. The research work’s primary objective is to thoroughly investigate the design of a VSI and its impact on operational performance, particularly under conditions of a weak grid, while simultaneously upholding established power quality standards. In order to attain this goal, it is imperative to gain a comprehensive understanding of how the inverter functions within a distribution network. A weak grid is more susceptible to voltage drops, harmonic distortion, and equipment failures. This is because the higher impedance can cause the voltage to drop more as the current flows through the grid. It can also amplify the effects of harmonic distortion and make it more difficult for equipment to operate reliably. Also, weak grids can undermine sustainability by increasing energy losses, reducing reliability, increasing the cost of electricity, and limiting the integration of renewable energy.
Key Words: Controller stability criterion, Heuristic optimization technique, Power quality, Total Harmonic Distortion, Weak grid condition, Impedance-based stability, Standalone microgrid system.
1.INTRODUCTION Grid Connected Inverters (GCIs) have become a critical component of modern power systems, enabling the integration of various Distributed Energy Resources (DERs) into the main utility grid. These DERs encompass a range of capacities, categorized as lower/small level (less than 10 kW), medium level (10 – 1000 kW), and higher level (1 - 10 MW), each with distinct operational requirements [1]. To ensure the reliable and safe operation of these systems, a set of international and national standards, including those governing operational principles, power quality, safety
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