To prepare for the future high penetration level of renewable energy sources, the power grid’s technical boundaries/constraints for the correct operation of powerelectronics interfaced devices need to be further examined and defined. This paper investigates the challenge of integrating Voltage Source Converters (VSC) into low inertia power grids, where the system frequency can vary rapidly due to the low kinetic energy buffer available, which used to be provided by the rotational inertia of synchronous generators. The impact of rate of change of frequency (ROCOF) on the PLL dynamics and its subsequent influence on the VSC power stage output is explained. The Bonaire island network is presented as case study. The performance of the VSC is analyzed under a fast ROCOF event, which is triggered by a short circuit fault. A down-scaled experiment is used to validate the Bonaire island network simulation results. It shows that the phase angle error measured by the synchronous-reference frame phase-locked loop (SRF-PLL) is proportional to the slope of the ROCOF and inversely proportional to its controller integral gain constant.

No abstract

No abstract

No abstract

In modern buildings virtually all electric loads are non-linear. Neither the applicable standards for supply of electrical energy nor those for consumption of electrical energy take into account the replacement of linear loads by non-linear loads. Low power equipment is exempted in standards assuming that all other (linear) loads dominate the power quality. In modern buildings there is a huge number of non-linear loads in lighting, monitor, computer and small power supplies and only a very limited number (or no) conventional linear loads. This is causing unacceptable interference with costly consequences. This paper analyzes current standards and the (exemptions for) harmonic current consumption of modern devices. The increase in harmonic distortion in a new building due to a multitude of non-linear equipment is shown. This forced the owner of the building to make costly changes in the power supply network.