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• A novel generalized admittance criterion is proposed, significantly reducing the requirement for synchronous phasor measurements. • Harmonic contribution evaluation is simplified based on the proposed generalized admittance criterion. • The fluctuation characteristic of harmonics is considered for the harmonic admittance estimation. • The proposed method has comprehensive applicability and high harmonic source location accuracy. The widespread integration of various nonlinear power electronic devices in modern power systems has made harmonic distortion more serious than ever before. Given the urgent need to improve power quality, the harmonic contribution evaluation (HCE) is of great importance since it can provide a strong basis for harmonic mitigation measures. However, the conventional HCE methods are not effective due to the lack of synchronous voltage and current phasor information in real-field practice. To overcome the phasor limitation, an HCE method based on a generalized admittance criterion (GAC) is proposed in this paper. The proposed GAC aims to determine the dominant harmonic source at the point of common coupling (PCC) from the utility side and customer side. Compared to the conventional method, the developed method only needs the RMS values of the PCC voltage, current, and phase angle difference. Therefore, the synchronous phasor information of voltage and current is no longer required. Meanwhile, a threshold to determine the dominant harmonic source is established by using the equivalent admittance ratio on both sides of PCC. The evaluation process of the proposed method is significantly simplified by comparing the generalized admittance limit with the proposed threshold, which also greatly improves the method evaluation accuracy. Moreover, the interference of background harmonic fluctuation is excluded by using the linear calibration-based harmonic admittance estimation method. Finally, multiple scenarios with various admittance characteristics were simulated to verify the performance of the proposed criterion, and the real-field measurement is also used to demonstrate the accuracy and validity of the proposed method. [ABSTRACT FROM AUTHOR]

• The framework combines a cloud-edge-end structure to break the information barriers of multi-source measured data. • The method executes different strategies according to voltage levels based on interaction of edge computing is proposed. • Harmonic source identification and evaluation are achieved through the multi-level interaction of edge computing. • TVE, CMHSE and HHSE method for cloud-edge-end collaborative computing strategy are developed into the system. With the increase of power electronic devices such as distributed renewable energies, energy storage, and flexible loads, the disturbance sources are rapidly raised and distributed in multiple voltage levels in the distributed network. The harmonics they produce are random and uncertain, and the massive amounts of data propose high demands on server computing capability, which restrict harmonic sources evaluation and significantly influence the judgments of the power quality in the distribution network. In order to improve the power quality and the harmonic source evaluation function of the distribution network, in this paper, a framework for multi-harmonic source identification and evaluation based on cloud-edge-end collaboration is proposed. Firstly, based on the analysis of the functional requirements harmonic sources evaluation in multiple voltage levels, a novel framework of cloud-edge-end collaboration is proposed. Secondly, the cloud-edge-end collaborative harmonic sources evaluation method which executes different service strategies according to voltage levels and grid operation based on the multi-level interaction of edge computing is proposed. Further, the working principle of the proposed novel framework with multiple evaluation methods including the dominant harmonic source identification, concentrated multiple harmonic sources evaluation (CMHSE) and hierarchical harmonic sources evaluation (HHSE) is described in detail in order to show the completed work processes of the proposed framework. Finally, the performance of the proposed method is verified based on the real data measured from different realistic urban power grids in China. The proposed method can effectively evaluate harmonic contributions in distribution systems and in turn provide a basis for harmonic mitigation measures. [ABSTRACT FROM AUTHOR]

With the rapid development of renewable energy resources, harmonics in modern distribution systems have become more serious owing to the wide adoption of power electronic devices. Today, distribution-level phasor measurement units (D-PMUs), which can provide synchronized harmonic data with high-time resolution, are being rapidly developed. To utilize the D-PMUs, a hierarchical harmonic contribution (HC) determination method is proposed in this paper for systems with multiple harmonic sources. The HCs were determined using a widely linear complex partial least squares (WL-CPLS) method, which is both accurate and efficient. In an actual power system, the D-PMUs are not fully installed at all buses and the harmonics monitored by each D-PMU are actually the aggregate effects of multiple harmonic sources in the subarea. Based on the above consideration, a hierarchical HC strategy is proposed to locate the main harmonic contributors, layer by layer. The proposed method can be applied to a radial distribution system with any number of D-PMU placements. The methodologies are explained and verified using the IEEE 37-bus system. The real case study results based on the demonstration project are also analyzed in this paper. [ABSTRACT FROM AUTHOR]