Abstract
Smart Cities can benefit from existing municipal low voltage (LV) distribution grids by supporting public services with permanent power supply and providing grid connection points to distributed generators (DG). The increased integration of DGs and inverter based non-linear loads increases voltage quality issues, thus the cost-efficient assurance of voltage quality in LV grids with long radial lines is of increasing importance for the operators of municipal electricity distribution systems. Conventional methods for mitigating voltage quality issues (e.g., power line renovation) might not be optimal solutions either technologically or economically. Existing studies do not address all relevant issues related to the assurance of required voltage quality in such LV grids. This paper provides an overview of the applicability and rationality of traditional as well as alternative methods to solve voltage problems in LV grids. The authors use DIgSILENT PowerFactory software to simulate the performance of voltage stabilisers under different conditions. The authors propose a robust method for the classification of LV feeders and provide recommendations on how to resolve voltage quality problems, with the help of different power quality improvement devices, where the traditional methods of upgrading to medium voltage and grid reinforcement are economically infeasible. Based on our results, recommendations for mitigating voltage quality problems in LV distribution grids with radial lines of different lengths are given.
Highlights
A key characteristic of an electricity distribution system is its ability to ensure a reliable and quality power supply to connected loads and distributed generators (DG)
The study reported in [8] states that the uncontrolled charging of PEVs has negative effects on network demand, voltage unbalance factor (VUF), and the voltage profile of the low voltage (LV) distribution grid, while [9] lists line congestion, voltage drops, inverse power flows, increased energy losses, and power quality (PQ) as problems related to DG and PEV charging stations
We describe theoretical studies and a robust methodology to solve voltage quality problems using different power quality improvement devices, which provide an alternative to traditional methods of grid reinforcement and the transition to medium voltage lines
Summary
A key characteristic of an electricity distribution system is its ability to ensure a reliable and quality power supply to connected loads and DGs. Most residential electricity consumers are single-phase loads contributing to the voltage unbalance phenomenon that is always present, to some extent, in low voltage distribution networks. Similar issues may present themselves in distribution networks with DGs and/or a significant amount of unbalanced or non-linear inverter-based loads, posing new challenges for DSOs. Since the classical grid reinforcement approach to mitigate the described problems requires significant investments from the DSO, alternative measures have been investigated. It was determined that there is additional need for novel or improved methodologies that provide alternatives to conventional approaches in solving voltage problems in low voltage grids. We describe theoretical studies and a robust methodology to solve voltage quality problems using different power quality improvement devices, which provide an alternative to traditional methods of grid reinforcement and the transition to medium voltage lines. We present the theoretical analysis using simulations carried out with the DIgSILENT GmbH modelling software PowerFactory [29]
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