Dutch companies are facing problems because the quality of electricity is deteriorating, reports Financieele Dagblad and NOS last week. The pollution is caused by devices that consume less power, including charging stations. But what are the consequences of this reduced power quality? And what can we do about it? Paul Broos and Thijs van Wijk of the EladerNL foundation provide an answer.
“This is about what we call 'power quality'”, explains Paul Broos van Elader. “The electricity grid has alternating voltage (AC): 3-phase current flows through the cables in a sine shape. Nowadays many modern devices, including all electronics, only operate on direct voltage (DC). Then the AC of the grid must be converted into DC. That happens in your phone charger and in your laptop adapter. The battery in an electric vehicle is also DC voltage. So when you charge an electric car or bus, you have to switch from AC to DC voltage. With smaller charging capacities, this happens in the vehicle (for example if you charge an electric passenger car at a public charging station in the street), with larger charging capacities in the charging station.
Faults and wear
If the conversion of AC into DC does not proceed neatly, the sine shape of the current is disrupted. Many devices have filters that make them insensitive in practice. But in extreme cases, power quality problems can lead to malfunctions (eg in electronic equipment), faster wear or even malfunctions.
“To explain this, a little more background is needed,” adds colleague Thijs van Wijk. “This is due to the fact that a modern inverter, such as in electric vehicles NZ (EVs), is more efficient than old inverters, because they can switch at a higher frequency. However, this switching can also cause a high-frequency current to be emitted from the inverter onto the grid. A manufacturer can take measures against this, but is not obliged to do so. These high-frequency disturbances - or supraharmonic as they are now known in the scientific world - are not yet described in the product standards. So nobody actually does it wrong in this area, but we want to move to a situation that describes what is right and what is wrong. This should actually be the main message. ”
Less efficient loading
You also have other forms of disturbed voltage quality, says Van Wijk. For example, reactive power may be involved; this is energy that is required by a device and must be created and transported somewhere through the grids, but cannot be used for useful work. So it reduces the efficiency of the grid and of the loading. A device can also have a high switch-on peak. “A high inrush current of a device can cause the voltage of the grid to drop briefly to a lower value. Sensitive electronic devices can stop working or, if repeated frequently, even fail. ”
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