Introducing small storage capacity at residential PV installations to prevent overvoltages

Low voltage distribution feeders are designed for unidirectional energy supply from transformer to consumer. However, the implementation of small-scale PV production units on local utilities may result in bidirectional energy flows. The simultaneous power injection at sunny moments may cause a serious voltage rise along the feeder. These overvoltages may not only damage critical loads but also switches PV inverters off causing loss of green energy at the most productive moments. This paper presents a method to limit the voltage rise by introducing small battery buffers at local production sites. A smart inverter decides whether the PV energy is injected in the grid or buffered in the batteries. The relation between battery buffer size and overvoltage reduction is presented for a typical Belgian residential distribution feeder. The influence of the buffer along the feeder is calculated by working with synthetic load profiles and solar irradiation data

Scalable data storage for PV monitoring systems

Efficient PV research which includes a prolonged data monitoring from multiple experiments with different characteristics, requires a scalable supporting system to handle all of the collected information. This paper presents the development of a relational database for hosting all the necessary information for data modeling, comparative analysis and O\&M systems. Ramer-Douglas-Peucker algorithm and Timescaledb compression are used to decrease the size of the time-series data and increase the performance of the queries. A decision-making algorithm is presented for selecting the optimal inputs to the Ramer-Douglas-Peucker algorithm to ensure the maximum disk space savings while not losing any of the necessary information. Furthermore, alternative ways of implementing the same database are provided.Comment: Editor: Geert Deconinck. 18th European Dependable Computing Conference (EDCC 2022), September 12-15, 2022, Zaragoza, Spain. Fast Abstract Proceedings - EDCC 202

Investigating methods to improve photovoltaic thermal models at second-to-minute timescales

This paper presents a range of methods to improve the accuracy of equation-based thermal models of PV modules at second-to-minute timescales. We present an RC-equivalent conceptual model for PV modules, where wind effects are captured. We show how the thermal time constant $\tau$ of PV modules can be determined from measured data, and subsequently used to make static thermal models dynamic by applying the Exponential Weighted Mean (EWM) approach to irradiance and wind signals. On average, $\tau$ is $6.3 \pm 1~$min for fixed-mount PV systems. Based on this conceptual model, the Filter- EWM - Mean Bias Error correction (FEM) methodology is developed. We propose two thermal models, WM1 and WM2, and compare these against the models of Ross, Sandia, and Faiman on twenty-four datasets of fifteen sites, with time resolutions ranging from 1$~$s to 1$~$h, the majority of these at 1$~$min resolution. The FEM methodology is shown to reduce model errors (RMSE and MAE) on average for all sites and models versus the standard steady-state equivalent by -1.1$~$K and -0.75$~$K respectively.Comment: 24 pages, 11 figures, 8 table

De speed pedelec: fiets, bromfiets of…?

status: publishe

Speed pedelec rider’s behaviour as input for appropriate legislation

status: publishe

E-steps, monowheels, hoverboards: hoe passen we onze wegcode aan aan nieuwe vormen van mobiliteit?

OPINIE voor VRTNWS: https://www.vrt.be/vrtnws/nl/2018/08/10/opinie-duurzame-elektrische-mobiliteit/status: Published onlin

Speed pedelecs: waarom en hoe?

status: Published onlin

Maximum assistance factor of four for speed pedelecs?

Presentation for the industry at Eurobike 2017status: publishe

Potentieel van de speed pedelec: Is dit een game changer?

status: publishe

Shipping in a Calm at Flushing with a States General Yacht Firing a Salute

Detail of the boats at left; This is one of the earliest examples in Dutch marine painting of a "parade" picture, which shows ships assembled for a special occasion. The stately yacht at center fires a salute while a dignitary is conveyed to shore in the sloop at right. The porpoises gliding through the calm waters were known to frequent the busy port of Flushing (Vlissingen). In this early work, van de Cappelle displayed his ability to capture the effect of reflected light on water. Source: The Getty [website]; http://www.getty.edu/ (accessed 7/10/2010