Power quality now concerns us all
Identify and rectify network problems at an early stage
At the latest with the start of a so-called energy turnaround, the voltage quality in electrical distribution grids (= power quality) is becoming increasingly important. Ideally, the voltage in electrical networks has a sinusoidal shape. This is determined by voltage level, frequency and curve shape.
Example of an optimal sine wave
What has changed
Due to the interaction of changed grid conditions and the increased use of non-linear consumers and generators, phenomena are increasingly occurring. As a result, the individual sinusoidal shape of current and voltage is influenced. This leads to changes in the power quality and can cause unwanted symptoms for other consumers. This in turn is a possible trigger for unplanned costs for operators of electrical installations as well as for end users.
Mains quality – simplified
Paul has a headache – although his core values are right
Heart rate is okay
Blood pressure is okay
No loss of blood
… but still a headache. Why?
The environmental conditions for “headaches” have changed:
- Increase in non-linear consumers and producers
- Centralised feed-in with grid reaction
- Decentralised feed-in (e.g. PV, etc.)
- Micro grids with internal grid feedback (e.g. data centres, etc.)
Interim summary
One could prevent a previous illness, and thus the resulting symptoms, with a preventive screening. But who likes to go to the doctor to find out that something is fundamentally wrong?!
HOW TO DETECT NETWORK PROBLEMS?
Permanent grid monitoring helps to detect grid phenomena at an early stage and prevent system failures. With modern PQI– preferably metrologically certified class A devices – all common disturbance variables and voltage events can be permanently recorded and evaluated. In addition, it is possible to detect dangerous insulation faults at an early stage with the help of a permanent residual current measurement.
Example of real waveforms in the network
Typical examples of phenomena occurring due to poor power quality:
- Overheating of motors & transformers
- Unwanted disconnection of residual current devices and fuses
-
Overload of the neutral conductor (fire hazard)
- Overloading the Power Factor Correction capacitors
- Flickering of fluorescent lamps and monitors
- Failure of electronic ballasts
- General functional impairments of electronic devices & controls (e.g. lift controls, telephone systems, production systems, measuring equipment, etc.)
- Unintentional shutdown of servers (e.g. in data centres, etc.)
- Impairment of the transmission of ripple control signals (e.g. in distribution networks, etc.)
- Interference as well as false alarms from radio-networked smoke alarms
- Increased reactive energy and therefore increased energy costs (ǂ energy efficiency)
- Reduction of the expected lifetime of components (e.g. failure of LED lighting, failure of servers, motor failure, transformer failure, etc.)
- Disturbing noise development (in the frequency range up to 16 kHz for the human ear)
- Skin effects as the tendency of a high-frequency alternating current to flow only through the outer layer of a conductor
- Line and cable damages
- u. v. m.
Poor power quality therefore burdens and impairs electrical consumers and, in the worst case, can endanger people and property. A study in 2007 already put the economic damage caused by network phenomena at 157 billion euros per year. This is a strongly growing trend. Power quality is therefore not a new topic, although it has come more and more into focus in recent years due to an increasingly technologised and also more vulnerable world. The consideration and the limits for the electrical phenomena are derived from the standardisation for electromagnetic compatibility of IEC 61000-x-x.
Conclusion
As soon as faults or failures occur in a network or in equipment, either continuously or sporadically, which cannot be explained under normal professional troubleshooting conditions, the cause is often impaired power quality.