DC-side High Impedance Ground Fault Detection for Transformerless Single-phase PV Systems
Abstract: With the fast
development of the photovoltaic (PV) industry, techniques of improving solar cell
efficiency, reliable and low cost inverter and advanced fault detection methods have
been introduced. This thesis is focusing on ground fault detection on the DC side of a
PV system. Ground fault detection interrupter (GFDI) has been implemented in PV systems
to detect ground faults and ... read moreopen the circuit during fault operations. However, GFDI is
only effective for low impedance ground fault. For high impedance ground fault (HIGF),
GFDI will not be triggered since there is not enough fault current flowing through the
device. HIGF should be cleared in a PV system; otherwise, potential hazards will induce
fire accident of the PV generation plant and it will result in electrical shock of
system operator. A common mode current detection method has been adopted in this thesis
to distinguish normal operation and HIGF operation of PV systems. Common mode model of
PV system is derived which combines stray capacitance of PV arrays and stray parameters
of inverter and power transmission line. Normal operation and HIGF operation will
display different characteristics at common mode resonant frequencies. PSIM simulation
results validate the feasibility of our common mode current detection
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Electrical Engineering.
Advisor: Alex Stankovic.
Committee: Hanoch Lev-Ari, and Ronald Lasser.
Keyword: Electrical engineering.read less