Voltage drop model analysis in determining the voltage transformer for grid feeder [EMBARGOED]

Abstract

The Voltage Regulating Distribution Transformer (VRDT) stands as an on-load tap changer (OLTC) transformer capable of regulating voltage across all three phases. While its design has been extensively discussed in the literature review, no prior studies have explored its application in the context of Photovoltaic (PV) energy penetration in low-voltage (LV) grids. This PV injection in LV grids increases challenges in ensuring stable voltage control because of the backward flow of the current from the LV grids. Hence, the application of VRDT with the presence of PV injection can be studied by simulating it. Thus, this research objectives are to investigate the voltage drop model and VRDT architecture, develop an enhanced voltage drop model using Microsoft Excel as well as MATLAB/Simulink based on PV penetration for the low-voltage distribution system, and analyze and validate the enhanced voltage drop model using the develop distribution in MATLAB Simulink. Consequently, this research presents a novel, refined voltage drop model tailored for International Islamic University Malaysia’s (IIUM) distribution network. The proposed model is constructed in Microsoft Excel using a derived mathematical equation, which is subsequently validated and analyzed by comparing it with Matlab/Simulink's modeling platform. The simulations are conducted under four distinct scenarios: 1) without the implementation of VRDT and PV injection, 2) with the implementation of VRDT but without PV injection into the grid, 3) without the implementation of VRDT but with PV injection into the grid and, 4) with the implementation of VRDT and PV injection into the grid. The study's outcomes demonstrate that PV penetration can induce instability within the distribution network, with varying degrees of voltage deviation corresponding to different percentages of PV injection. Moreover, the modeling approach establishes that integrating a VRDT into an LV grid effectively facilitates voltage adjustment under loaded conditions and uninterrupted PV injection. This research contributes to understanding the potential benefits of VRDT in improving voltage stability and accommodating PV sources in LV grids. The findings highlight the importance of considering VRDT as a viable solution to enhance the performance and reliability of distribution networks amidst increasing PV integration.