Analysis and calculation method of critical voltage of DC commutation process considering AC system single-phase fault moments

Abstract

This paper takes a close research on the impact of voltage reduction in a single phase as well as its occurring moments on commutation failures (CFs). When there is a sudden voltage reduction in a single phase, the change rule of post-fault magnitudes and phases of commutation voltages is researched theoretically. On the basis of the change characteristic, valves that are most probable to suffer from CFs are carefully elaborated. Moreover, a method for calculating critical voltage of a single phase considering different fault moments is developed. As long as the phase voltage is lower than the critical voltage, it may result in a CF. In addition, the change regularity of critical voltage along with different fault moments and phases is given. All the analysis and theoretical calculation results are validated by simulation in PSCAD/EMTDC.

Keywords

• power transmission control
• commutation
• power convertors
• power grids
• fault diagnosis
• power system simulation
• power transmission faults
• different fault moments
• theoretical calculation results
• calculation method
• critical voltage
• DC commutation process
• AC system single-phase fault moments
• single phase
• occurring moments
• commutation failures
• sudden voltage reduction
• post-fault magnitudes
• commutation voltages
• phase voltage