New Metric Recommended for IEEE Standard 1547 to Limit Harmonics Injected Into Distorted Grids

Abstract

IEEE Std. 1547 defines grid connection standards for distributed resources (DR). This standard sets requirements for harmonic performance, which are particularly relevant when converter interfaced DRs are considered. Specifically, the standard limits the allowable harmonic current injected by a DR, assuming grid voltage at the point of common coupling (PCC) is harmonic free. In this paper it is demonstrated, both mathematically and experimentally, that the harmonic current injection of a converter interfaced DR depends highly on the level of PCC background voltage. The paper presents a mathematical formulation that enables the impact of PCC voltage harmonics on the harmonic current injection of a converter interfaced DR to be determined via experimental identification of the converters Frequency Coupling Matrix (FCM). Experimental tests show that an IEEE 1547 compliant solar inverter with measured TDD of 0.66% for an undistorted PCC can produce TDD levels in excess of 20% in the presence of 3% voltage distortion. It is concluded that TDD metrics, as employed in IEEE Std. 1547, provide little insight into the field performance of converter interfaced DRs when background voltage harmonics are present. Improved FCM-based metrics for assessing harmonic performance of converter interfaced DRs in presence of voltage harmonics are provided.

A Piecewise Bound Constrained Optimization for Harmonic Responsibilities Assessment under Utility Harmonic Impedance Changes

“…With the development of smart grids, increasing numbers of power electronic devices have been connected to distribution networks, which inject a large amount of harmonics [1][2][3][4][5]. Various electrical power equipment and electronic products have a strong sensitivity to the harmonics in the distribution network, making harmonic elimination of great importance [6].…”

Using Frequency Coupling Matrix Techniques for the Analysis of Harmonic Interactions

“…Such detailed information is not typically available to customers. It has been recently shown that the FCM of a power converter can alternatively be obtained with a high degree of accuracy from simple experimental measurements at the terminals of the converter, with the converter considered as a "black box" [20], [21]. This paper builds on the experimentally identified FCM model of a converter to systematically solve for harmonic interactions between the grid and the converter.…”

“…Recently, a measurement-based approach was examined for directly determining the FCM via experiments [20], [21]. This approach requires no knowledge of the converter topology, parameter values, nor controller details.…”

“…Assuming the FCM model is experimentally determined as in [20], [21], it is desirable for the FCM to be integrated into a grid model, thus enabling the study of harmonic interactions between the converter and the connected ac network. For the FCM to be used in presence of grid impedance, the FCM representation of the converter should remain constant despite variations in ac network voltage harmonics.…”

A Comprehensive Design Approach of Power Electronic-Based Distributed Generation Units Focused on Power-Quality Improvement

“…For instance, reference [8] deals with the power transfer capability problem of DGUs including harmonic distortion, and considering power quality regulations at a speci c point of the network. Reference [9] brings out some pitfalls of electric power quality indexes allowed by international regulations showing that being within the limits is not enough in order to ensure proper performance of the DGUs electrically close to each other. In more sophisticated approaches, the power quality on the distribution system is improved by the use of harmonic compensation methods in the control schemes of the interconnected DGUs [10]- [14].…”