Online Determination of Varying Harmonic Load Contribution to Grid Voltage Distortion

One of the challenges of the power quality management is the need for reliable harmonic identification in grids with multiple nonlinear loads. This paper presents a method for accurate real-time assessment of varying harmonic contributions of nonlinear loads. The method can be referred to as invasive using ternary pulse sequences as injected stimuli. The performance of the proposed approach is demonstrated using the Simulink-based model of a power system. Simulations in typical grid situations verify that the proposed algorithm is robust to a realistic environment and can be used for the weak grids featuring frequent topological changes, containing power factor capacitors and significant nonlinear loads with abrupt changes of operating modes. The influence of measurement imperfections on the accuracy as well as the application limits of the method are also analyzed.