Voltage compensation in multi-grounded distribution network with a three-phase five-wire DSTATCOM.☆

Abstract

This paper presents a three-phase static synchronous compensator with five legs to be connected to a multi-grounded neutral distribution network. Several strategies are proposed in the literature to compensate for the imbalances in multi-grounded networks. Typically, three-phase static synchronous compensators with four legs can compensate for positive-, negative- and zero-sequence network voltages. However, they cannot simultaneously compensate also for the neutral voltage of multi-grounded network. Thus, the fifth-leg of the proposed compensator is controlled as a single-phase converter in order to compensate the neutral-voltage at the point of common coupling. Linearised mathematical models, in the synchronous reference frame, are developed and used to design the controllers used to compensate the network’s neutral voltage and to regulate the current synthesized by the fifth-leg of the compensator. A multi-grounded network, derived from the IEEE NEV test feeder, is modelled in the PSCAD/EMTDC to investigate the performance of the proposed compensator. The results of the digital simulations demonstrate the effectiveness of the neutral voltage compensation strategy and validate the control loops designed for the three-phase five-wire static synchronous compensator.