Inspection of interharmonic emissions from a grid-tied PV inverter in North Sweden

Abstract

The main objective of the paper is to investigate the existence of interharmonic emissions from an MPPT driven grid-connected PV inverter, identify their severity and persistence. The presence of interharmonics in the measured current from a PV installation is linked to direct and diffused solar irradiation as well as a high ramping rate of the irradiation causing variations in both active and reactive power. The paper sets forth a set of observations and inferences, which is an appendage to the ongoing research on the power quality aspects of solar power. Three different case studies are evaluated in detail using signal processing tools like STFT and FFT.

Mitigation of Interharmonics in PV Systems With Maximum Power Point Tracking Modification

“…To address this issue, a model to predict the interharmonic characteristic in PV systems has been proposed in [8], where the results from the interharmonic model agree well with the field observation in [6]. It has been demonstrated in [8] that the interharmonic characteristic is strongly dependent on the MPPT algorithm parameters such as the perturbation step-size v step and the sampling rate f MPPT .…”

“…One of the emerging power quality problems for grid-connected PV systems is the interharmonics, which are defined as the frequency components that are non-integer times of the fundamental frequency [1]. Recent studies have reported that PV inverters are the potential source of interharmonic emission for PV systems, which have been observed both in the laboratory testing environment and the field measurements [2]- [6]. Although the interharmonics standard regarding the emission limit is still under development, the interharmonics can cause grid voltage fluctuations, flickering, and unintentionally disconnection of (Corresponding author: Ariya Sangwongwanich).…”

“…According to the previous studies [3]- [6], the Maximum Power Point Tracking (MPPT) operation is one of the main causes for interharmonics in PV systems. In particularly, the perturbation of the PV arrays voltage during the Maximum Power Point (MPP) searching inevitably induces power oscillations at the dc side, especially during the steady-state operation.…”

Interharmonics in PV systems: a review of analysis and estimation methods; considerations for selection of an apt method

“…Some of the reported and possible causes of interharmonic emissions in PV systems are: dynamic changes in the solar irradiance caused by fast cloud passages and ramping rate events (especially in large PV plants) [7,8]; inefficiency of PV inverter maximum power point tracking (MPPT) control strategy [9][10][11]; reactive power management in inverters [7,12]; active islanding techniques [7,12,13] and interactions due to secondary emissions from other connected devices [14]. The identified challenges associated with the measurement and analysis of interharmonic emission from PV are summarised and listed below:…”

Analysis of Power Flow Under Non-Sinusoidal Conditions in the Presence of Harmonics and Interharmonics Using Geometric Algebra

“…Currently, they are not a real or compelling problem, but it is expected that in the future they may become so, therefore it is necessary to pay attention to this problem [8]. For example, Ravindran and Bollen [9] investigates the existence of interharmonic emissions from an MPPT driven grid-connected PV inverter to identify their severity and persistence. Kim et al [10] also talk about the impact of interharmonics on offshore electrical systems and how interaction with other harmonics can cause serious vibration problems that cause systems to shut down.…”