Condensatorbatterij verbetert de arbeidsfactor

Bedrijven waar veel inductiemotoren ingezet worden, kampen doorgaans met een slechte cosinus phi. Dit komt doordat de spoelen in deze motoren veel blindvermogen (reactief vermogen) vergen. Hoe groter het aandeel reactief vermogen ten opzichte van het aandeel actief vermogen, hoe lager en dus hoe slechter de cosinus phi zal zijn. Indien de cosinus phi onder een grens van ca. 0,9 zakt, zal de energieleverancier het bedrijf in kwestie een boete aanrekenen. Via een goed gedimensioneerde condensatorbatterij kan het bedrijf echter zelf het benodigde blindvermogen opwekken en aldus een boete vermijden

Influence of grid configuration on current conducting behaviour in PV installations

On the roof of an industrial site a 385 kWp PhotoVoltaic installation is operational. When production of this system reaches 60% of the installed power, the circuit breaker trips. At sufficient production, measurements show a high distortion of phase voltage and variable waveform of both phase voltage and current. Analysis of the installation showed that a Yy0 transformer is used introducing a high zero sequence impedance. Unbalance in the injected current combined with a high zero sequence impedance leads to a high neutral-ground voltage and distorted phase-neutral voltages. In this paper it will be shown that the tripping of the circuit breaker is caused by the measurement method of the device. This paper analyses the practical measurement results, causes of errors and the solution to the stated problem

Technical SWOT analysis of decentralised production for low voltage grids in Flanders

The increasing energy prices, combined with high funding by the government, has resulted in a massive integration of decentralised electrical energy production units in Belgium. These systems are mainly PhotoVoltaic systems and the sudden increase of both number and power ratio of the DG systems has put additional stress on the distribution network. In this paper a technical SWOT analysis is presented. The researchers believe that the solution to decompress the stress can result in additional benefits for both, end user and distribution network operators

Measurement-based modelling and validation of PV systems

This paper presents the analysis and results of modelling of various photovoltaic (PV) systems. Two general models are discussed and presented: an analytical model and an equivalent circuit model, both formulated for main PV technologies currently available on the market. Analytical model does not require any PV system specific input data or parameter, and is formulated as a generic performance model of a considered PV technology. Equivalent circuit model, however, requires specific input data and adjustment of the model parameters, in order to provide an accurate representation of a modelled PV system. The paper provides direct comparison of models based on manufacturer’s specification data and available measurements, as well as the discussion of obtained results

Maximum power injection acceptance in a residential area

The number of installed distributed generation (DG) in residential areas rapidly increases, specifically in the form of photovoltaics (PV), causing some undesired side effects such as voltage rise. Overvoltage can damage critical loads, but is also disadvantageous for the owner because inverters switch off in case of overvoltage, resulting in output loss. Voltage limits are investigated through calculation and simulation of the voltage profile in a typical low voltage (LV) grid by using load data. Insolation data is used for the particular case of PV. This paper presents practical guidelines for the maximum power acceptance in a residential distribution network and the estimation of PV production loss due to overvoltage

Profoto : proefveld voor fotovoltaïsche toepassingen

Zonnepanelen, ook PV-installaties genoemd, worden meer en meer toegepast als alternatieve energiebronnen op kleine schaal. Voor de residentiële gebruiker is het niet altijd duidelijk welke zonnepanelen ze best kiezen. Door het opbouwen van een proefveld voor fotovoltaïsche (of zonne-) panelen van de verschillende hedendaagse technologieën worden verschillende types zonnepanelen naar opbrengst onder identieke omstandigheden met elkaar vergeleke

Test field for LV distribution systems

Detailed analysis of an actual Low Voltage distribution grid is often difficult due to practical considerations. Designers generally use simulation tools to predict the behavior of the distribution grid, although parasitic effects are hard to predict and even harder to model accurately. In this paper an actual, but free programmable, distribution grid is presented which enables detailed analysis of nearly all the electrical parameters of a residential distribution grid. Although this paper focusses on the design of this demonstrator project, some suggestions to future research are indicated

Tripping of circuit breakers in PV installations due to zero sequence field impedance

On the roof of a wool processing company a 385 kWp PV installation is installed. When production of the installation is more than 60% of the rated power the circuit breaker trips. Measurements show high THD(U) of phase voltages and variable waveform of both voltage and current. Analysis of the installation showed that a Yy0 transformer is installed introducing a high zero sequence field impedance. Unbalance in the injected current combined with a zero sequence impedance leads to high voltage drops and distorted phase voltages. Measurements also show high RMS values of the current in the neutral conductor. Analyses show that the tripping of the circuit breaker is caused by the measurement method of the device itself. Higher current values are calculated due to multiple zero crossings of both voltage and current. This paper gives the practical measurement results, causes of errors and the solution to the stated problems