Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads

Abstract

Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P -Q(V) nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.

Non-characteristic Harmonic Analysis of Uhv ac/dc Systems

“…For uhv direct current transmission system, the important link is the commutation link and inverter link of the converter station [5][6]. Therefore, through a typical double-bridge rectifier station, the current characteristics of the uhv dc system were analyzed when operating under the working condition 4-5 [7].…”

A Harmonic Compensation Strategy in a Grid-Connected Photovoltaic System Using Zero-Sequence Control

“…The system also consisted of twin Nonlinear Loads (NLLs) including three-phase diode rectifier as well as three unbalanced single-phase diode rectifiers generating the bent wave structure. The nonlinear loads are responsible for producing the distorted waveforms [38,39]. A proposed control methods were applied to PVs and the values of the three-phase power band and control system are presented in Tables 1 and 2, respectively.…”

A Framework to Analyze the Stochastic Harmonics and Resonance of Wind Energy Grid Interconnection

“…The p-value indicates the probability that the chi-squared distribution under a certain degree of freedom is larger than the chi-squared value obtained from Equation (5). If the p-value is less than 0.05, for example, the assumption of the probability is proven to be false.…”

“…Integrating high penetrations of variable renewable sources into the electric power grid presents a range of unprecedented grid operations and planning challenges requiring new study approaches and tools so that the impacts of a proposed wind power plant (WPP) can be properly assessed prior to interconnection [1][2][3][4][5]. In particular, increasing attention has been drawn to power quality concerns: harmonics and the output harmonic impedance of wind turbines (WTs) and the aggregating WPP are stochastic due to the inherent intermittency of the wind and wide control bandwidth of the power electronics interfaces [6,7].…”