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Power-electronic sources, such as Type 3 wind turbine generators and static synchronous compensators (STATCOM), interface to the grid through, partial- or full-scale, and power converters that have inherently fast switching capability to control their output current during short circuits. The short-circuit current is a function of the specific converter control algorithm and differs significantly from the conventional rotating machine sources without converter interfaces. Therefore, if a transmission-line protection scheme is designed for conventional sources, (not taking into account these differences in short-circuit current characteristics), reliability can be at risk. Using real-life short-circuit currents on lines supplied by sources having a power converter interface, this paper illustrates the reliability risk to conventional line protection schemes, in particular, to those which use negative-sequence quantities for the detection of unbalanced faults. This paper discusses the protection schemes, adopted by BC Hydro–a large Canadian Electric Utility, for transmission lines interconnecting Type 3 wind turbine and STATCOM sources. Their application for ground faults is independent of the converter control algorithm as long as the source is interconnected to the grid via a transformer which is a source of zero-sequence current. [ABSTRACT FROM PUBLISHER]

Single-phase trip and high-speed reclose (SPTR) schemes applied on extra-high-voltage (EHV) lines offer significant benefits over three-phase schemes as they help maintain synchronism and stability in sparse transmission networks. However, a secondary arc may persist and prevent timely recovery of the air insulation. In this situation, high-speed reclosing will attempt to re-energize the still-faulted line, adding stress to the system instead of benefiting the system from the SPTR scheme. Using staged fault and fault disturbance data recorded from several 500 kV lines, this paper presents validation of an enhanced hybrid scheme incorporating secondary arc extinction detection logic designed to avoid high-speed reclosing onto faults while also allowing single-phase reclose in cases where it would be successful. The new logic is now being applied to several 500 kV lines in BC Hydro to improve transmission system reliability. [ABSTRACT FROM PUBLISHER]