Considerations on harmonic current emission limits in the Netherlands illustrated with two case studies

The Dutch Grid Code sets limits on harmonic voltages that the grid operator (e.g. DSO) must comply with. Harmonic emission from the customer’s installation needs to be restricted so that the DSO can meet the harmonic voltage requirements for all customers as indicated in the Grid Code. At present, information on harmonic emission limits is available in several standards, including those established by IEC and IEEE, and in the D-A-CH-CZ handbook. In the Netherlands, regulations on harmonic current limits are available (from 1997), but these are no longer adequate for present grids and need updating. This paper is a first start towards this goal and provides several considerations that must be investigated further. The need for updating is confirmed by the random week measurements at various network points. It was observed that, in general, total harmonic distortion (THD) levels in the medium and low voltage Dutch grids are quite stable. However, several violations of standard limit values for individual harmonics (such as the 5th and 7th harmonic) have occurred at different nodes in the grids. In the last years, the DSOs have also registered some harmonics related complaints. It is noticed that a few big customers in the network are (often) producing significant harmonic currents which are propagating at different network points and could ca use disturbances to other customers. In this paper two such cases are discussed and the need for an up to date harmonic current emission standard is emphasised.