Abstract
Power-distribution grids consist of assets such as transformers, cables, and switches, of which the proper utilization is essential for the provision of a secure and reliable power supply to end customers. Distribution-system operators (DSOs) are responsible for the operation and maintenance of these assets. Due to the increased use of renewable sources such as wind and solar, grid assets are prone to operation conditions outside safe boundaries, such as overloading, large voltage unbalance, and a rise in voltage. At present, distribution grids are poorly monitored by DSOs, and the above-mentioned problems may thereby go unnoticed until the failure of a critical asset occurs. The deployment of smart meters in distribution grids has enabled measurements of grid variables such as power, current, and voltage. However, their measurements are used only for billing purposes, and not for monitoring and improving the operating condition of distribution grids. In this paper, a state-estimation algorithm is proposed that utilizes smart-meter data for offline analysis, and estimates the loading of grid assets and power losses. Single- and three-phase state-estimation algorithms are compared through simulation studies on a real-life low-voltage distribution grid using measured smart-meter data. The three-phase state-estimation algorithm based on the nonlinear weighted least-squares method was found to be more accurate in estimating cable loading and line power losses. The proposed method is useful for DSOs to analyze power flows in their distribution grids and take necessary actions such as grid upgrades or the rerouting of power flows.
Highlights
≤ε no yes According to the analysis described in [39], the polar node voltages (NV) Distributionsystem state-estimation (DSSE) takes slightly fewer iterations on an average for convergence compared to other forms, such as branch current
Power flows at the substation were less estimated by both the 1φ and the 3φ DSSE algorithm, which resulted in them underestimating power losses
The 1φ DSSE algorithm uses a single-phase-equivalent model of the distribution grid, which has the limitation of considering nodes with loads connected at only one or two phases, and lines that connect only a single phase or two phases between nodes
Summary
The increasing rate of the integration of renewablesource-based power generators, which have a distributed nature, caused a major change in the operation of distribution grids [1]. Due to the integration of renewable sources, distribution grids are experiencing unprecedented challenges such as voltage rise, reverse power flows, and the short-term overloading of cables and transformers. The impact of harmonics on grid power losses was assessed in [3]. The presence of harmonics can have destructive impact on grid components, including distribution transformers. A study on the impact of grid harmonics on a substation transformer can be found in [4]. Grid assets, including substation transformers and cables, are not monitored on a regular basis due to a lack of adequate measurement infrastructures
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