Improved D-StatCom control for operation with unbalanced currents and voltages

Abstract

This paper presents a new D-StatCom control algorithm which enables separate control of positive-and negative-sequence currents and decoupled control of -and -axes current components. The algorithm is based on the developed mathematical model in the -coordinates for a D-StatCom operating under unbalanced conditions. The problem of dc-side voltage ripple and ac-side harmonics generation due to unbalanced voltages/currents is solved by using switching function modulation, enabling the use of a relatively small capacitor on the dc side. The control algorithm is also suitable for high-power applications using multipulse voltage-source converters. The algorithm is tested by means of detailed simulation using PSCAD, where the performance is validated in the case of severe network fault and in the case of unbalanced load compensation. The compensator voltages are generated by means of pulsewidth modulation.

Application of Distribution Static Compensator (D-STATCOM) to Voltage Sag Mitigation

“…In [9], a repetitivebased controller for a D-STATCOM is presented that compensate reactive power, but it offers more calculation complexity. [10], presented a D-STATCOM control algorithm which enables seperate positive and negative sequence currents, but the presented method needs more time than the control method that perenetd in this paper. This paper presents a study of a D-STATCOM (Distribution Static Compensator) used for mitigating voltage sag.…”

Control of a Single-Star Flying Capacitor Converter Modular Multi-level Cascaded Converter (SSFCC-MMCC) STATCOM for Unbalanced Load Compensation

“…The connection of a VSC-STATCOM to an unbalanced network causes the appearance of a second harmonic component on the converter's dc side. This, if not eliminated, generates low order harmonic current on the ac side resulting in further deterioration of the power quality [1]. The situation becomes particularly difficult when the unbalance is continually varying as occurs with large industrial loads such as arc furnaces.…”

“…The situation becomes particularly difficult when the unbalance is continually varying as occurs with large industrial loads such as arc furnaces. Various schemes reported have been shown to be effective for compensators based on converters with common dc links such as the two-level full-bridge or classical multilevel converters [1]. The general approach has been extracting, and hence eliminating, negative-sequence components from the load current and cancelling as much as possible the harmonic components on the dc-voltage.…”

A Comprehensive Analysis and Control Strategy for Nullifying Negative- and Zero-Sequence Currents in an Unbalanced Three-Phase Power System Using Electric Springs

“…Such power imbalance can be classified as short-term and long-term [1]. For short-term imbalance, unbalanced currents are relatively larger than those of the long-term ones.…”

“…For short-term imbalance, unbalanced currents are relatively larger than those of the long-term ones. They are caused by unsymmetrical faults such as the phase-toneutral short circuit in power lines and equipment failures [1]. If these large unbalanced currents are not properly handled, generator trips can occur [2].…”