Verification of tool for allocation of harmonic current emissions considering frequency-dependent impedance

Simple tools with sufficient accuracy are needed to calculate the impact of new customers on voltage quality. This paper presents the results, findings and conclusions from the verification of a tool for calculating harmonic current emissions limits based on IEC 61000-3-6. The main advantage of the tool is the estimation of the frequency-dependent impedance using a simplified network model. In most cases, this allows higher harmonic current emissions limits for new customers and thus lower costs for connecting new nonlinear loads for the customer. In addition, the tool is easy to use for DSOs and can enable grid reinforcement deferral. The tool also provides more knowledge about the low-frequency resonances in the grid and can thus support the filter design and converter control. However, the simplification of modelling only the main feeders can lead to large discrepancies in cable-dominated grids or when a significant cable near the customer is not modelled. In these cases, modelling of the main branches is also required.

Inspec keywords: power distribution planning; IEC standards; power distribution reliability; power supply quality; power grids; power distribution economics; power system harmonics

Subjects: Distribution networks; Power supply quality and harmonics; Reliability; Control of electric power systems