Field Harmonics Measurements and Computer Simulation of an SVC at the Mongolian Transmission Network

Abstract

The static var compensator (SVC) mainly consists of a thyristor-controlled reactor (TCR) and a fixed capacitor (FC). In 2020, the install capacity of SVC was 30 MV Ar, which was connected to the South Energy System (SES) of the Mongolian power system (MPS). The primary purpose of the SVC is to compensate reactive power, increase voltage stability and reduce voltage fluctuations. However, TCR generates a high level of harmonic currents because of the thyristor's firing angle control. Therefore it is necessary to determine the effect of harmonics generated by the SVC on the power system and its components. To perform these analyses, it is needed to determine the harmonic characteristics of the grid at the point of SVC connection, existing levels of harmonics, and appropriate standards regarding acceptable harmonic levels in the power system. To calculate and design harmonics, an accurate harmonic model should be created in the simulation software. For example, the 6-pulse converter model of the DIg SILENT PowerFactory has not considered phase angles for unbalancing the system. Hence, the importance of modelling angles of the harmonics, measuring instrument, analysis of various waveforms are of interest to all engineers. Hence, in this paper, a harmonic model is considered harmonic current phase angles measured by a real system.