PV-Arc Detection - Circuit supervision using DC-Arc Detection in PV systems on dwellings.
Starting point / motivation
Photovoltaic systems installed on buildings nowadays are designed to maintain high levels of DC-voltage. In addition to that the necessary inverter is usually installed closely to the "point of common coupling" (PCC).
As a result the DC wirings in urban PV systems are getting more and more complex. One of the drawbacks of DC wiring is that electrical arcing can occur at connectors and other kinds of contact wiring. Caused by the high energy maintained by the PV generator severe fire hazards can result from such arcs.
Based on this, development requirements have been established by regulation authorities in the USA. They require a mean to detect and interrupt occurring arcs defined under very narrow conditions of ignition. The detection of more realistic arcs is a task that is far more challenging to achieve since the variety of conditions of ignition is huge. Therefore conventional threshold detection algorithms are insufficient for a reliable detection. Our experience from the USA shows that the main challenge is to detect a big variety of possibly occurring arcs and keeping the number of false positives as low as possible at the same time.
Contents and goals
The goal of this project is to research fundamentals of electrical arcing with PV sources in order to find classification methods including low energy arcs and unclear conditions of ignition in a serial and parallel arcing situation. From our point of view the increased fire safety as an outcome of this project is one of the key requirements necessary for the sustainable and save implementation of photovoltaic in urban communities.
The approach to reach our goal is to gain the knowledge to find the key relevant factors for detection of realistic arcs by establishing test setups and parameters. Finally the main goal is to find pattern recognition methods based on laboratory- and field-evaluated data.
The basic research that is conducted here provides a way to avoid false positives and increase fire safety in PV systems in Europe, regardless normative requirements which may arise.
Fronius International GmbH