Assessment of the THD Problem in the Southern Governorates Desalination Plant

The problem of the Total Harmonic Distortion (THD) in the Southern Governorates RO Desalination Plant was first raised when the newly installed PV solar system inverters did not successfully integrate with the plant while being on the backup generators mode. The PV system contractor, reported that the THD levels in the plant are higher than the acceptable standard level. He suggested installing external filters on the Variable Frequency Drive (VFD) devices to reduce the THD levels in the plant network. The main contractor submitted a Variation Order of over 500,000 EUR for installing external filters for both phase-1 and phase-2 production lines of the plant. The aim of this work is to conduct power analyses of the plant and carry a comprehensive survey to identify the THD levels of the existing phase-1 plant under all different running scenarios, diagnose the problem and to identify suitable solutions.