Quality of power supply in power distribution systems requires continuous measurement using power quality analyzers installed in the grid. The paper reviews the published methods for optimal location of metering points in distribution systems in the context of power quality metering and assessment. Three methods have been selected for detailed analysis and comparative tests. It has been found that utilization of the methods is possible, but their performance varies highly depending on the test grid’s topology. Since the methods rely on the state estimation approach, their performance is strictly related to observability analysis. It has been found that standard observability analysis used for typical state estimation problem yields ambiguous results when applied to power quality assessment. Inherited properties of the selected methods are also analyzed, which allows for the formulation of general recommendations about optimal selection of metering points in a distribution system.

There are currently more than 30 underground mines operating in Poland. These are mines extracting hard coal, salt, and metal ores. Each of these plants has its own specifics for operation, but all operate under the same regulations. The basic principle is to ensure the safety of the crew and equipment. The progressive mechanization and automation of the mining process results in the installation of power electronic converters in the networks of mining plants, which significantly deteriorate the quality of the power in the plant supply networks. In addition, the constant reconfiguration of these networks related to the progress of the work can affect the safety conditions of the plant. This article describes problems occurring at one underground mining plant that are related to the structure of the power grid. Failures and interruptions in the production process were the result of poor power quality. They directly translated into increased production costs and significantly affected the safety level of the workforce, which could result in further consequences, not only in the financial sphere. The article also addresses the issue of existing legal regulations, the provisions of which may be insufficient in assessing the current state of power quality in mining plants.

In recent years, electricity distribution system operators in Poland have installed tens of thousands of balancing electricity meters, in accordance with the requirements of the Polish Energy Regulatory Office, with the function of measuring the quality of electricity supply indicators. These meters offer new possibilities in the assessment of functioning and diagnostics of power distribution systems. The article presents the possibility of using aggregated 10-minute power quality measurement data from dispersed electricity meters to locate dominant sources of disturbances in the power network of the Polish distribution system operator – TAURON Dystrybucja S.A.

The paper presents the results of an experimental study, which was conducted in 2021 and briefly presented at the conference CIGRE Paris Session 2022, as a part of a joint initiative for comparative studies of PV inverters, of AGH University of Science and Technology and Tauron Dystrybucja (Polish DSO). The study was performed on a representative sample of 29 brand new PV inverters, widely available for sale in the EU, from over 20 various manufacturers from and outside the EU. For the purposes of this research, all tested PV have been made available by their manufacturers or regional distributors, which confirms the origin of the devices from official distribution channels and their designation for the EU market. The conducted research covers the technical aspects of PV inverters’ operation and performance included in the NC RfG network code, technical standard EN-505049-1:2019, and internal regulations of distribution system operators governing PV inverter technical quality and its cooperation with the low-voltage distribution network. The national regulations may differ between individual EU member states. The paper describes the testing procedure, obtained results, conclusions, and recommendations for regulatory bodies and DSOs.

Hoisting machines are among the largest loads in mining power networks. Due to frequent start-ups and stoppages, there are the source of numerous disturbances in the power network of a mining plant, such as: higher harmonics or voltage fluctuations. Currently, in most machines, the power supply and speed control system is based on static power electronic converters, which results in increased efficiency of the system and better regulation capabilities, but may increase the negative impact on the quality parameters of electricity supply in the power supply network of a mining plant. The article presents an analysis of the influence of a change in the power supply system of a hoisting machine on the electric power quality parameters of a mining plant network on the basis of measurements of power supply systems of two hoisting machines, before and after modernization.

The article presents a method enabling estimation of the selected power quality indicators at a given point of a power network, on the basis of the power quality indicators recorded at the nearest vicinity points. For needs of the estimations, artificial neural network algorithms were applied. The result is a neural model that defines the relationship between the power quality indicators of the same type, at adjacent points. The paper presents results of analyses and tests under real operating conditions of the distribution system.