Field test results of serial DC arc fault investigationson real photovoltaic systems

Abstract

DC arcing faults pose a safety risk in already existing photovoltaic systems. Due to the aging of the photovoltaic system components enhanced by environmental factors and the high DC voltages, long-lasting arc faults can occur and may cause serious damage. Conventional fault protection methodslike circuit breakers or fuses -are only able to clear faults if they carry a large fault current. Compared to arcing faults in AC installations DC arcing faults in photovoltaic systems have a bigger hazard potential. This is mainly based on the favorable conditions of existing. That is first of all missing zero-crossings of the current and the fact that a solar generator regarded as a source of energy cannot be turned off. Secondly a solar generator is a distributed energy systems with a big amount of potential places of origin for arc faults. Because of the non-linear current-voltage output characteristic of photovoltaic systems a lot of arc faults cannot be detected or even extinguished by common fault protection methods. Moreover it does not only ensure a higher arc-stability but also a wider range of stable arc operating points. Furthermore ambient conditions (e.g. solar radiation, temperature, etc.) and the arc length extend the range of stable arc operating points tremendously. For those reasons the characterization of DC arc faults in photovoltaic systems by means of measurement in real existing photovoltaic systems is indispensable. Especially under consideration of the increasing number of accidents with photovoltaic systems involved. This paper will include a general description of the infrastructure used for measuring and recording arc voltage and current. In addition, the experimental test setup used to insert a series arc fault within a PV system and to generate comparable results under safe conditions will be explained in detail. Furthermore the field test results of serial DC arc fault investigations in photovoltaic systems with different module technologies and taking into account a wide range of environmental conditions and a huge variety of different fault locations within the solar generator will be presented.Index Terms--electric fault, arc fault, DC arc, photovoltaic system, arc fault generator, arc fault measurement

Review of DC Series Arc Fault Testing Methods and Capability Assessment of Test Platforms for More-Electric Aircraft

“…1) Temperature: The impact of temperature on arc fault characteristics has briefly been touched upon in [60] for PV systems. The temperature was varied in equal steps in a range from −20 o C to 60 o C, and it was noticed that the arc fault current increases with temperature.…”

“…2) Real System: In direct contrast to the previous approach where a simplified circuit is used, there is the option to apply and study DC arc faults in a real system using actual hardware equipment. This approach has been performed in existing PV systems as reported in [60], [63], [72], [74]. An example testbed is shown in Fig.…”

A Novel Algorithm for Fast DC Electric Arc Detection

“…Then, the measured data need to be processed. Various tests have been conducted to select the most efficient algorithm and descriptor for the detection of arcs in household mains [48][49][50][51][52] and photovoltaic installations [53][54][55][56][57]. For both AC and DC systems, among others, the following signal processing algorithms have been taken into consideration: Wavelet transform and Fast Fourier Transform (FFT) [1,[3][4][5]28,29,58,59]; Short-Time Fourier Transform (STFT) [38,42,48]; Finite Impulse Response (FIR) filtration and derivative [51,[60][61][62]; Wigner-Ville Distribution (WVD) [11]; Signal-to-Noise Ratio (SNR) [27]; statistics [26]; and mathematical morphology [30].…”