Power quality indices and objectives

Abstract

System operators are encouraged to report information relating to power system performance towards external parties, such as users and regulators. Some power quality indices have already been defined in standards, others are still missing. The joint working group CIGRE C4.07/CIRED (formerly CIGRE WG 36.07) has collected available measurement data and existing indices for MV, HV and EHV systems and recommends a set of internationally relevant power quality indices and objectives that can be seen as the outer envelope of performance for each power quality parameter. This paper will present the results of the work accomplished by the working group CIGRE C4.07/CIRED. The paper sends also a message to equipment manufacturers to provide monitoring equipment able to measure the recommended indices and to implement the flagging concept, as introduced in IEC 61000-4-30. It is expected that once published, these recommendations will also help facilitate the future presentation of power quality d ata to third parties, typically regulators and customers.

Non-equal DC link Voltages in a Cascaded H-Bridge with a Selective Harmonic Mitigation-PWM Technique Based on the Fundamental Switching Frequency

“…Furthermore, the proposed SHM-PWM in single-phase converters employs a 150 Hz switching frequency for each of the switches to achieve similar results. In this paper, four power quality standards (EN 50160 [4], CIGRE WG 36-05 [5], IEC 61000-3-6 [6], and IEC 61000-2-12 [7]) are considered for the proposed SHM-PWM method. The selected grid codes in this paper are more intransigent than those in previous works [12], [17], [23], [24].…”

“…2) The proposed SHM-PWM modulation technique considers the lowest voltage harmonic limits for several standards such as (EN 50160 [4], CIGRE WG 36-05 [5], IEC 61000-3-6 [6], and IEC 61000-2-12 [7]). Thus, the solutions of the proposed technique can meet all of the power quality voltage limits.…”

Robust probabilistic optimal voltage sag monitoring in presence of uncertainties

“…In addition to voltage sag's frequency of occurrence, residual and duration of voltage sags have been proposed to characterise voltage sags. However, a widely used index is the system average root mean square frequency index recommended by IEEE, CIGRE and CIRED [23–25].…”

Four-Legs D-STATCOM for Current Balancing in Low-Voltage Distribution Grids

“…Since most of the problems for consumers are caused by voltage imbalances and not current imbalances, the most important standards define the voltage unbalance factor (VUF) and their limits. ANSI [19] recommends VUF values lower than 3 % since IEC [20] and CIGRE [21] set the limit at 2 %, allowing to reach 3 % in networks with a high presence of single-phase customers, to ensure the quality of supply. The negative sequence has direct consequences on the malfunctioning of induction machines.…”